I just spent a while deleting something like 100 - 120 spam tracebacks. I could disable all of them, or restrict them to only Windows Live Spaces, but that seems broken. Given that the spam will happen, I'd much prefer to see better UI for batch deleting.
For anyone with the same problem, if you go to the blog itself and open them associated with their entries instead of doing it at the editing home page for the space, it is much more efficient. You can mark a bunch and then delete them in bulk, instead of a single delete followed by a whole and slow as hell refresh of the page.
I'm still liking Spaces overall, but I believe they've got a lot of work ahead of them to keep ahead of the game. Their strength is working at a scale that is hard for others in the industry to compete with, but I'm not sure they've got the speed others do.