I'm not sure we get enough posts in the "Announce your Product" section to have this matter (yet), but i did think of 2 things we could do if we end up getting too many self-promotional posts there:
1) require that only after a few normal posts can you post an announcement there
(this might be traditional approach to cutting down adverts but im not sure it accomplishes what we want since some new coders/companies would want to tell us about their software for the first time they come to the site and not really a big reason why they shouldnt be able to).
2) require that only programmers or those who are directly involved in the product *creation* are allowed to post such announcements -- not company public relations people/marketers/hired affiliates. i like this one -- it basically says we want to hear about your product but not if its just from someone doing paid posting, etc.