So far I have seen similar numbers for an app that I released about a week and a half ago. I've been tracking hits to the http://www.phrasememe.com website and the demo video on Youtube ( http://youtu.be/6T_v4x9JtLQ ) and there seems to be around 250-350 downloads so far (IE: clicks on the zune download link). The App Hub reports are a week delayed, so it only shows around 200 official downloads but stops reporting after the 16th. On the 19th it was listed as #779 out of the top 3000, so it only takes a few hundred downloads to get you into the top 25% right now.

I think having a trial mode helps a lot, as out of the 200 downloads there were only a dozen or so purchases. My app is pretty generous on the trial (nagware basically) so I don't know if that ratio will increase much or not, but there are always other ways to monetize a high traffic application. My goal right now is actually to break into the top 10% of apps, but we'll see if that is in the cards or not.