After doing an untethered jailbreak on my Apple TV 2G (ATV2) with GreenPois0n RC6, I noticed that if I rebooted the Apple TV my wifi would not reconnect. Disconnecting the power and plugging back in would not resolve the issue. After a bit of research, I figured out a quick fix to getting my wifi back:

Go to: NitoTV > Settings > Restart Lowtide

After the device rebooted, my wifi connection re-established itself within 10-15 seconds. To permanently fix the issue, I SSH'ed into the AppleTV and issued the following commands:

apt-get update
apt-get remove com.nito.nitotv
apt-get install com.nito.nitotv
killall AppleTV

Update (2/20/2010): A number of blogs are reporting that greenPois0n RC 6.1 includes the wifi fix directly. So if you haven't already flashed, just go ahead and use 6.1 and it should include the wifi fix. Additionally, you can always flash RC 6.1 over your current setup, but I find it easier just to either remove/install com.nito.nitotv or install OpenSSH from the nitoTV menu.

Update (2/16/2010): NitoTV recently posted on their twitter account the the wifi issue appears to be related to SSH -- they recommend that you grab OpenSSH from the top of the nitoTV featured list and reboot to fix the wifi issues. You shouldn't need to do both fixes (the commands above and the OpenSSH install), but it also shouldn't hurt anything.

On Wednesday 16th February 2011, @nitoTV said:
the wifi fix is live!! thanks @saurik and @DHowett for major contributions 
to squelching the problem! it was an SSH issue and saurik has updated 
openssh to 5.8p1-9. grab openssh from the top of the nitoTV featured 
list and reboot and your wifi woes /should/ be history!!!

Note: If you are running a tethered jailbreak, it's recommend you update to an untethered jailbreak such as the GreenPois0n RC6 jailbreak. fireCore also has out a beta version of their seas0nPass utility. However, with the untethered Windows version of GreenPois0n being out for Apple TV 4.2.1 devices, I don't see why you wouldn't just want to use the GreenPois0n release as it's just as user friendly... well, at least as user friendly as a jailbreak can be.

Drives Mounted as Odd IDs? (UUID)

If your drives are showing up as long IDs that look similar to "5f3d2340-b3c7-4c47-ba9a-ceaa9e699a4f" (from df -T command), there are a number of things that may have caused this. I've found that if my partitions are all labeled and the nodiskmount flag is still present in my grub configuration, then I no longer have this problem.

Whenever I install XBMC, one of the first settings I change is I enable auto mounting of drives. It's a relatively simple change, but requires you modify a file on the filesystem.

For Ubuntu Lucid 10.04:

I've noticed that it's not necessary to manually remove the nodiskmount option on 10.04 (grub2). The modifications that I used to make in /boot/grub/menu.lst on Ubuntu Karmic, I now have to make in /etc/default/grub on Ubuntu Lucid.. When I removed the nodiskmount on Ubuntu Lucid I started having some issues with the disks being mounted in odd ways (eg. my NTFS drive being mounted directly to /media). What I found is that instead of removing nodiskmount, if I just properly labeled my partitions, they would automatically show up properly -- you can label your partitions using the e2label command.

As I noted in the comments below, you may still need to remove nodiskmount in Ubuntu Lucid to get your eSATA drive to mount (especially true for people who followed my Revo 1600 guide). What I found is that because the internal drive on the Revo 1600 is NTFS, it will cause the weird issues I mentioned above. If you happen to fall into this case, I would highly recommend you check out my article on Drives Being Mounted with Odd IDs. The article explains how to find the unique identifier (UUID) for your drive and manually create an FSTAB entry to mount your drive with your specifications each time the system loads. Now that I've wrapped my head around how FSTAB works, I prefer to use this method as it lets me set my own unique name, path, and other settings for how the drive is mounted.

However, if you'd still like to modify the grub parameters for other reasons, I've included the details below...

Open the file /etc/default/grub:

sudo nano /etc/default/grub

Find the line for loading your system (usually starts with GRUB_CMDLINE_LINUXDEFAULT) and make sure it's not the commented out line that often comes default at the top of the file. Modify this line so it no longer has the nodiskmount option in it.

Save the file and close it. Ctrl+O, Enter, Ctrl+X.

Run the following line to update grub and then reboot:

sudo update-grub
sudo reboot

For Ubuntu Karmic:

If you are still booting from the XBMC-Live 9.11 Camelot USB stick directly, this will be in the syslinux.cfg file. If you have installed XBMC to disk, this is in the /boot/grub/menu.lst file. 

To remove this flag from the menu.lst file, telnet into the XBMC machine (use the instructions from the sabnzbd install post if you don't know how), then open up the file with your favorite editor:

sudo nano /boot/grub/menu.lst (you may have to enter your root username and password -- typically xbmc / xbmc)

Arrow down to the first line under "## ## End Default Options ##" near the bottom of the file and on the "kernel" line arrow to the right until you see the "nodiskmount" text. Delete this text then press Ctrl+O [enter] to save the file then Ctrl+X to exit. Reboot your box and you should now see some new items in your file manager usually named something like sdb1 or sda1.

NewzBook is an application I wrote to centrally manage my downloads and media. It has integration points with various indexing sites, SABnzbd, media management, etc. I originally designed the application for the Popcorn Hour, but I am now using XBMC again. I personally use the XBMC Live variant, so I've written up some instructions so other XBMC Live users could also use my NewzBook app.If you haven't heard of NewzBook before, I would recommend checking out this thread on the NMT forums which describes what it does... I've also attached a few screenshots after the jump below.