Better late than never. Here's hoping that the submission-and-approval process goes smoothly for Cave Story. It sounds like the developer has been incredibly thorough though, seeing as its release was delayed, like, four times or something crazy.
I'm also glad that they have officially confirmed additional content, but one thing at a time, Nicalis. They're only a small team, so they should have the sense to spread out the DLC over the latter half of 2010. If they are overly ambitious, the extra levels may fall flat and we certainly don't want that.