NoteBook is a really great product, but (and I know this is nit-picking) I think it's time to bump up the version number, because they've been fluffing around with "2.1" for almost 2 years. It's hard to remember what you've got when they insist on using build numbers.

2.1.1, 2.1.2, 2.2... try it out and leave the stupid numbering systems to Mozilla and their products that don't break through to n.0.1 (I realize they're reserving certain digits for security updates, others for feature updates, others for significant product changes, etc, but they never use them; "2.0.0.14" is just stupid).