1- Installed WordPress 2.9.2
2- Upgraded to WordPress 3.0 alpha using the Beta Testers plugin - OK
3- Installed BuddyPress - OK
4- Created test users and groups with custom avatars - OK
5- Installed the multi-sites network: Everything seems to work fine, the users are there and no data was lost with one exception: the custom avatars are missing. Tried to upload a new custom avatar but it doesn't show on the crop screen. Checking the folders wp-content/uploads/avatars I've verified that all the custom avatars are still there and if you upload an image it's stored there bu it doesn't show on screen.