Unless there was a major design revision since news of the VentureStar scrapping, I believe that it doesn't have scramjets (which are still in early prototype stages).
Rather, it has aerospikes, which are much more similar to conventional engines, just that the anatomy's inverted (sorta hard to explain, esp. since I'm not very clear on them myself. It's been a while)
Also, that is one massive plane. (with a rather small cargo bay)
Here's an idea: why doesn't NASA buy Russia's giant Antonov, refine it, and use that as a first stage for the new spaceplane? seems like what they're going for anyways, if VentureStar is indeed scrapped.
Also, there's talk of a nanotube space elevator that this guy (too lazy to look up his name) claims he can build that'll basically be a tethered satellite in geosynchronous orbit. It'll have solar cells on the elevator lifts (which use rollers to grip the tether to travel up/down), powered from the ground by high-powered lasers to ferry equipment to the top end of the tether, where they'll be launched.
Sounds like BS to me, since geosynchronous orbit is few times higher than his proposed height, and winds are a b---- with such large equipment. Also, since carbon nanotubes are extremely good conductors, wouldn't their movement through Earth's nonuniform magnetic field create current up and down the tether? New source of clean power? (Big phallic symbols, too)