Here is essentially what Pontiac (Jim Hopson, a Pontiac representative per the article) told Edmunds.com regarding the base price and standard features and options when they test drove the 2006 prototype.
The base model will retail at $19,995.
That price includes 18 inch rims, the full sport suspension, and 4 wheel disks.
Available options will include leather, upgraded audio, fancier wheel finishes (I assume chrome), a limited slip differential, and an auto transmission will be available late.
Their specification page also lists the following ammenities, most likely as options but possibly a couple standard as well:
ABS, fog lights, power windows, mirrors, audio and cruise controls on steering wheel, 6 disk in dash cd player, OnStar.
I doubt there will be a lot of power options on the base car, but its not going to be equipped like a base 1985 Yugo either! :lol
Here is the whole article:
http://www.edmunds.com/future/2006/pontiac/solstice/100380124/preview.html