Guild Wars 2 has been testing the gem (cash) shop in each of the BWEs. In this final BWE, they are doing it for real: you really buy gems, which you can use this weekend and then they will be reset for release. I find this an interesting economic model, and not necessarily a bad plan on their part, but I’m only as far as thinking, “…interesting.”
If you’re going to pre-sell the game, why not pre-sell the bonus toys, too?
Character slots seem to be $10 each, but I’m not sure where folks got the quote of 800 gems/slot. The game launches with 5 races, 8 classes, and 5 character slots (across all servers, characters are not server-bound except for WvW purposes).