I just returned from the ModernBill hosting conference, and am very pleased with what I saw of the application. I don't believe it's 100% feature-complete yet, though it's pretty close. The developers said that they'll be making tweaks to the UI and to some of the minor feature workings, based on feedback from the conference. (It was very informative, by the way. Two of us attended, and we're both glad we did. There were some industry- and general business-issue discussions, as well as plenty of MB-specific talks with the developers.)

We don't currently use ModernBill, and from what I heard at the conference, I'm glad we waited. It won't be an "upgrade" so much as a "migration", the changes to the database are that profound. The UI is easily customizable, multibranding support looks wonderfully solid, the accounting features are very very nice and will really make things easier come tax reporting time...but due to time constraints, I haven't downloaded any of the beta versions.

I'd love to know if anyone found the easter egg, though. I'm dying of curiosity...