Posting to Tumblr works just fine since the last update, for some exceptions. When I publish a post through MarsEdit and edit it afterwards, the changes do not show up on my blog.
Then when I edit the same post through the web interface, the changes are there, just the formatting lost, I have to redo this on the web.
A similar thing happens when I publish a private post to tumblr, open it in MarsEdit and update it as public - the formatting (on the web) is partly there, only paragraphs get lost. Also, sometimes when I set a post to be public afterwards, MarsEdit keeps endlessly asking me for my tumblr password. The only way to solve this is to delete the blog from MarsEdit and add it again. Then I can publish the same post from the local drafts.
I hope I was able to describe the issues appropriately since I am really confused about it myself.