i'm not convinced that app discoverability is a problem that needs to be solved. yes, there are 600K iOS apps and most of them are dying in obscurity. but that's a good thing. most of those apps are utter garbage and deserve to be obscure.

good, useful apps do not have a discoverability problem. it isn't hard to find the evernote app. i go to their website and get a link to it, or i type it in to the search box in the market. it is much more difficult to find an evernote rip-off, but why would i want to do that?

i find the list of obscure startup names tackling the app discovery problem to be fairly telling. if i've never heard of your discovery service, i won't be discovering much on it. they need to solve their own discovery problem before they attempt to solve anybody else's.