On my Apple TV 2 with XBMC installed and the latest versions I can get only the following ADDONS to work, as of May 8, 2011
Icefilms - which is terrific
HGTV - which is good
Yahoo Music Videos - which is good
Nothing else works for ADDONS. Looks like the originators of the ADDONS have moved ahead to other playforms to use there talents on.
Personally I like to have alternatives to XBMC ADDONS. The alternatives include:
PlayOn - which works great to stream HULU to my Apple TV 2.
PLEX - which is a free server app and Apple TV 2 app, and has potentials like XBMC
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I feel like an idiot. The plugins do mostly work. My XBMC was crashing on ATV 2 because I needed to install the NIGHTLY BUILD version on my Apple TV 2 (running 4.3 software). Now everything works mostly. Get the NIGHTLY BUILD here as a DEB file.
http://hadm.net/~keith/xbmc_atv2/
If you do not know how to install a DEB file (I taught myself in the last half hour), then please stay away from any attempt. There are loads of pitfalls. You have to learn SSH and with the PUTTY and WINSCP applications on windows platform. You also have to change the local HOSTS file on your APPLE TV 2.