A reader emailed me this picture of a Nikon D90:
For comparison here is the D80 - look at the differences. Too much details for PS job. This looks like the real thing:
and now compare the build in flash (below is the D80:
A PS-ed D300? Below is the comparison with D300:
We may find out tomorrow!
Update: This one goes down in the history of Nikon rumors as busted - many people thought that this was the real deal.