Sir Daniel Jalkut has released MarsEdit 2.4. He adds:

"I’m still working hard on a number of features that people have been asking for. Yes, I’m kind of a jerk when it comes to disclosing details about future releases"

Never feel like a jerk when doing this! I've learned the hard way to keep non-developed ideas to myself. There's no point in talking about future details unless they are already implemented and working they way you want. Otherwise, it just adds stress to your dev cycle.

You'll piss off your customers if you add the feature, it ends up sucking and you remove it. Best keep these planned features to yourself, and say something along the lines of "I'm considering it for a future release" when asked.