Hey, this script seems to work really well. I've been playing around with it to try to get my stuff over so that I can swap progs without much trouble some time soon.
Just a few caveats:
If you have a ' in the name of a category, it's going to choke. Easy enough to work around, since I only have one cat that has a ' in it, but there ought to be a way to escape these, no?
Also, it would be absolutely awesome if it didn't just import the categories, but also imported the blogs as top-level categories, and then insert the categories themselves as children of the top-level blog category. That would be ideal, since WP categories can do just about everything that multiple blogs can in b2evo, and then I could keep all my permalinks (mostly) stable through the transition.
I've got a lot going on the next few weeks, but if no one else can get to this sooner than me, then I'll probably look into it.
Anyway, thanks for the script! It's going to make this a lot easier.