This question is directed more at WPMU administrators vs. developers but either perspective is fine.
An obvious problem when importing from another blog service (ie: blogger, wordpress.com) is handling internal links. I’m curious how admins are handling this problem (if at all) when users import their existing blogs.
I’m considering building a plugin to do just that for my users, at least to a certain degree. My thought process is a single plugin that I can update the services for (right now I only care about wp.com, blogspot, typepad), added to the tools menu. Users would be warned warned they would need to revert their blogs back to whatever the defaults are before exporting (in case they’ve been able to change them). This should eliminate having to “figure it out”.
From that point, it shouldn’t be too hard to do a test against MySQL to see if it’s going to find anything, then actually doing the replace.