I've got my router setup with OpenWRT and it runs fine.
One thing I noticed since swapping to OpenWRT though is that Multicasting traffic appears to be blocked/stopped, thus breaking iTunes Wifi Sync and I'm sure a raft of other apple devices would fail if I tried to (Apple TV, maybe?)

I configured IGMP snooping and also tried Avahi-daemon, but don't appear to be getting far.

I can now get occasionally get iTunes to recognise my iPhone for Wifi syncing, but when I click "backup", it says backing up..... then fails. The phone then disappaers from iTunes, then reappears at an indeterminate time later.

The best I can think of at this point is that I haven't configured multicasting properly. 

Has anyone successfully set this up on their OpenWRT router?