Rodimus80-
This is a known issue with the current jailbreak, although it only happens to some users. My theory is that it's an issue with the tethered reboot corrupting something, rather than the jailbreak itself. The reason I say this, is that I have an ATV that I jailbroke back in December that worked fine for many reboots up until around Seas0nPass 0.6.8. I had to do a tethered reboot, and used that newer version for the first time to do it. When it came back up, I had no wifi. This has happened to me twice since then. This is a royal pain, as you know, because it requires a full restore, re-jailbreaking, and reinstalling everything.
I'm getting ready to redo that unit, and this time I'm going to do the tethered reboot with the Windows utility, to see if perhaps that will be more stable. Here's a couple of threads on that:
http://forum.xbmc.org/showthread.php?tid=91701
http://forum.xbmc.org/showthread.php?tid=92886
BTW, at least for me, I still can use hard-wired Ethernet on the unit when it goes into this state, but I don't have an easy way to run a cable down to that particular location, hence, I'm using wifi. I haven't figured out any way to revive wifi without a complete restore though, when that happens, and I've tried a lot of techniques.