On the CSV Import screen it would be nice if:
The default for "Import Source Tags and Categories" should be yes. Logically, if they are in the file, doesn't it make sense that the user would always want to import them? If you don't want to import them, then why would you put them in the file?
The default for "Tweet Events" should be no. If you're going to the trouble to import from CSV, odds are that you have a whole bunch of events and you probably don't want to tweet all of them at once.
While I'm wishing, would also be nice if it could remember the file so the next time it would default to the same file. As someone who imports several times a day, it would help!