Well, I can tell you that the 1.5 Mac Mini is legit. I heard the rumors about them, and after not seeing the update posted after the last two announcements I went ahead and ordered one anyway. I was pleasantly surprised to find that the Mini that arrived was the newer 1.5 GHz system, the other specs, as well as I could figure were:
64MB of Video RAM
5400RPM Drive (according to a model # lookup)
8x DVD+/-RW (I don't know about the Dual Layer part, as I'm too cheap to buy the discs, but I would assume it can do this)
My friend also said that it looks like they upped the Cache on the processor. I didn't really pay much attention to what it was previously, but I guess it's possible.
I can understand not wanting to order till the update is posted. I sold my previous mac mini in hopes of getting one of these. Maybe I just got lucky. Good luck to anyone else who's willing to throw caution into the wind.