First of all, anything deleted from the drive should be in the Recycle Bin.
Secondly, you should *not* point two operating systems or two use logins to the same folder as a Sync point, specifically for the reason that you encountered.
I am hopeful that your other PCs were not online and that should save you from trying to do too much recovery.
I also suggest that, once you recover the files, you make a copy of those files external to the Mesh. This is a beta and critical data without a safe backup should not be added to your Mesh as it can be lost if a bug is encountered.
It would be helpful for you to also file a bug. If you are unable to find the deleted files, please note that in the bug as data loss is a serious concern that the Live Mesh team needs to look at - even if it happened due to the multiple OS to one Sync point that you set up.
How to Submit Bugs and Live Mesh Logs
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator