I have scanned the data sheet specifications for Nokia N95 8GB, N81, 5310 XpressMusic and 5610 XpressMusic which is included in the press kit.
After reading through the specifications, I realized that N81 will come in 2 flavors, 1 with MicroSD memory and the other with 8GB internal memory (non-expandable).
Nokia N95 8GB will be using S60 3rd Edition, Feature Pack 3.1 operating system!
EDIT: Nokia website (http://www.forum.nokia.com/devices/N95_8GB) stated that N95 8GB is using FP1 instead. Hmmm.
EDIT2: Confirm it is Feature Pack 1.