Well, twothree things:
it's based on the IP address, so multiple hits from a single IP don't count -- could be several users from same IP.
it is cached and written in batches, to reduce database load. The threshold here is 10 and 5 (meta).
during private beta traffic is pretty low, relative to what it is when the site is public. So the views will be quite a bit smaller overall.
edit: I checked in a change to make the views a bit more reliable for some edge conditions, and I reduced the buffering threshold.