Here is all the info so far on release dates:
http://forum.ppcgeeks.com/showthread.php?t=125524
As for gingerbread it is hard to tell yet..I mean gingerbread hasn't even been released yet and no one knows what even the features in it are...so far samsung said they will be done with Froyo by early august (so it will be up to the carriers to just implement it or we can load a custom rom for it)