The announcements at MWC about Ovi Store included the revelation that N-Gage games would be distributed through Ovi Store. Although they aren't yet available through Ovi Store, they have started appearing in the Ovi Store website's "related content" sections for some games. (Clicking on them leads to a message saying they're not available, so perhaps they're in a pipeline still waiting for approval to go live.) See below for a screenshot.
Read on in the full article.
Slight update to this, if you search for N-Gage on the PC version of the Ovi Store website, you get 31 N-Gage demos and the N-Gage app itself listed in the results:
http://store.ovi.com/search?q=n-gage
None of them actually do anything if you click on them, presumably because they are waiting to be released.
I'm starting to wonder if this is a bug rather than a pre-release thing.
Maybe the N-Gage titles were meant to be there right from the beginning, but some technical problem is preventing their pages appearing when you click on them.
There are a few non-N-Gage games with this same problem, they appear in search results but when you click on them they're not available.