Hmm. They definitely launched with something over 10k, but when I talked with them in Austin at the end of October, they said they were closing in on 11k titles (probably there by now). But if you think about it that doesn't translate to all that many books per catagory. I asked at the local Barnes & Nobles how many titles they stocked in the store, and their best guess was upwards of 70k titles -- and still their SciFi section seems small to me!
I think there may be a hard limit on how many entries the searches return, if so, it's another example of stuff that needs work in the bookstore.
I think Amazon, et. al. probably have hard limits on what they'll show you, but their limits seem to be a bit higher than 500 entries.
