OK, here are some gotchas when you have 3000 entries like me:
# My hoster, Bluehost.com, seems to have some sort of limit. Or maybe it is MT that does, so only about 2,000 entries actually import properly. Unlike WordPress, you need to specify ahead of time what is the input format. So click on the Options in the Import menu and click on Textile for instance (that’s what I use).
# I had to split the 5MB file that was generated by MovableType’s export function into two pieces. Unfortunately because of the Unix vs. Windows weirdness on carriage returns (Unix expects only a return, while Windows wants a line feed and then a return), wordpad, vim, and pspad wouldn’t work. Only notepad seems to get this right. The input looks ugly, but it doesn’t insert extra characters. MT Import is picky and needs to have a Unix style text file.