Important news if you are just starting to publish direct to Amazon Kindle using their Digital Text Platform: the process may be easier than some of their help docs indicate.

In their help forums and documents, you will find contradictory information on their supported formats. A colleague just discovered that MS word/Open Office .doc documents work just fine. So start with .doc or html, which ever you know best, and possibly save yourself time and work.

Some of their help forums even say you need to run your doc through Mobi or Calibre, and while these can add nice touches, they actually are not necessary. Html formatted documents are their first choice. If you are familiar with html code, it does provide the easiest way to clean a document and remove any trouble-causing junk. But Word docs work too.

Amazon DTP Supported formats:
Zipped HTML (.zip)
Word (.doc)
Adobe PDF (.pdf)
ePub (.epub)
Plain Text (.txt)
MobiPocket (.mobi and .prc)

One caveat, the .doc that worked well here had already been formatted according to the far more stringent rules for Smashwords, so a lot of problematic styles, characters and formatting had already been removed.