Restoring Wifi on a Vaio Updated to Ubuntu 11.10

• You were running Ubuntu with a 2.6 kernel, say 10.10 or 11.04
• You let (or asked) update-manager to upgrade you to 11.10
• Now it doesn't even think you *have* a wifi interface.

I'll bet, like me, you'd previously told the 2.6 kernels to ignore the realtek 2xxx kernel modules, because it was causing an unfortunate mess.  And you did it scattergun style, blacklisting a bunch of them all will he, nill he, until it worked.  The shotgun method is a lovely, time-honored tradition .. you just gotta undo your work now that you're on a 3.0 kernel.

• `sudo vi /etc/modprobe.d/blacklist.conf`
• Find all of your "blacklist rt2something" lines and comment them out.
• If they're not there, check other files in modprobe.d
• Restart your cute little netbook.
• If that was the problem, on login, it'll connect to wifi as usual.

That was all it took for me to get my just-updated system back on the intarwebs.  Mine's a Vaio M111AX, but I think Sony used the same chips for other models.  If you really did a number on your module configuration for the 2.6 kernel, a clean install of Ubuntu 11.10 (Obsequious Ostrich) might be your best bet.  But hopefully this did the trick!