Good work Dan. You're certainly coming a ways with MacJournal. Couple of items that I would suggest that receive attention rather quickly:
1) Better WordPress support in the way of keeping a two way sync of blog entries so that you don't have to download them but rather always keep them sync'd in a folder
2) Show media such as embedded YouTube, Vimeo, whatever, videos and other media directly in the journal entries.

If you could get these in place and any other blog related WYSIWYG type of additions in place I believe you'll have a MarsEdit killer in addition to your regular other good feature set.