There is
new info at the Apple web site. The upgrade will be free for users with 1.0 or later.
The best feature in my book is that they appear to have abandoned their packages model of image archiving and will allow you to reference your images in their current location -- much like Lightroom
The new version also supports all of the current Mac hardware, and from the promo materials it sounds like some effort has gone into optimizing performance for them.
If you have the opportunity to attend one of the Aperture test drive sessions that are going around, I would recommend it -- it's three hours of hands on time with a 17" MacBook Pro and Aperture, it was very impressive.
Doug