First off. Love MarsEdit. One feature I would absolutely love in the next version is the ability to add categories to a Typepad blog.
But to the real issue. Typepad has Markdown support. MarsEdit allows Markdown syntax to be used when composing posts. Something that I have found is that ordered lists (ie. 1., 2., etc) when Marked Down in MarsEdit appears as plain text when posted. For example:
is turned into
1. Blah 2. Blah 3. Blah
From memory, I also had similar issues with unordered lists (ie. bulleted lists).
Other Markdown elements work (eg. URLs, emphasis, italics, etc)