MXM was a nice idea but it benefited consumers more than the GPU manufacturers (particularly because it allowed OEMs to switch GPU vendors without extensive re-engineering) so it ended up being more marketing than actual deliverables. And nobody -- OEMs or GPU vendors -- wanted the headache of having end-users swap out their GPU for something that blew the system's design thermal/power budget, and all the unreasonable bitching on the intrawebs that would inevitably result when the machines blew up or melted down.

No SATA2 - can't use OCZ's latest SSD drives. Deal breaker for me.

I really like the idea of a barebones laptop, especially since the markups are so high on CPU/GPU upgrades. But are these components easily available? In particular, compatable MXM GPUs? It seems pretty grim.
http://www.mxm-upgrade.com/

how much is it?

Seems like I haven't heard much about the MXM slot since around when the Dell XPS laptops were first launched.