I think I found a bug in using SMigrate to move a site - it's only a minor one.  I'm putting it here because I'm not sure where to submit bugs to Microsoft anymore, and I'm not willing to spend an hour to figure it out.

Here's the scenario: I used SMigrate to copy our production WSS site collection to some development servers.  It worked great, actually: the prod server was mis-configured to use a MSDE database rather than a Web Farm w/ SQL, but when I moved it to a server w/ that configuration, it moved the data into SQL just fine.  However, when I went to add a Web Part to the development server, it tried to connect to the old server's web part library.  I know this because it prompted me to log into the old server.

I'm not sure how to fix it quite yet, but I'm going to hack into the database in the next few days to figure out where it's storing the old server's name.  If I find anything, I'll update you.