Firecore has just updated its ATV flash (black) for TV 2 to beta 4 - this enables streaming media from NAS drives attached to TimeCapsules and AirPort Extremes!
Yep AFP support looks good: my experiments with streaming from my TC/Airdisk in XBMC (using SMB) lead to stuttering with some files, even though I can play them perfectly using the stock ATV interface with iTunes open and pointing to the same files on my TC.