Tripeedo (http://www.tripeedo.com) actually does this - I agree, it's a really nice way to let the user know they're ding the right thing. I find it a lot better than the traditional calendar widgets.

On the other hand, there are a lot of people out there who don't like the keyboard. It's easy to forget this, especially with so many people in CS and IT who try to never take their hands away from it , but there are a lot of potential users who would rather do everything with the mouse. Efficiency isn't a concern for these people (like my mom), since the input speed into the computer isn't ever their bottleneck, no matter how slow.

That said, nice job! I love natural language parsers!