The folks over at Mobile-Review.com have managed to get their claws onto a device running FP2 somehow - and have posted a rather long screenshot gallery to their web site.
For me, it looks like Nokia did a pretty good job at overhauling the user interface without breaking any existing applications and usage conventions - the new standby screen looks like a nice “home” for plug-ins; and the “third soft key” IMHO is just an extra label informing novice users about what the 5way center button currently does.
Personally, I see very little reason why this operating system should not work on older handsets - unofficially, some S60 folks told me that Nokia was considering this back at the Symbian Smartphone Show in London. However, marketing apparently wins - Mobile-Review is probably right about how no updates will be made available…
Get the full scoop here:
http://www.mobile-review.com/review/nokia-s60-fp2-en.shtml