Here's an odd one. I'll go check my site (bodensatz.quay.net) and at this point I'm not logged in yet. I look at "Who's Online" and at times it will say something like "13 Guests". OK, fine. That's expected.
But as soon as I log in with my account, all the guests disappear and it only shows me logged in.
I am running 1.3.5 and am not sure if it did this before my upgrade.