I don't know anything about this Pogo site, but I can tell you that it's easy to find out what OS the person is using. This information can be found using the user agent of your browser. For instance, a Mac OS X user who is browsing with Safari would have a user agent very similar or exactly like this:
Code:
Mozilla/5.0 (Macintosh; U; Intel Mac OS X *0_5_2; en-au) AppleWebKit/525.*8 (KHTML, like Gecko) Version/*.*.* Safari/525.*8
You can find out your user agent by going to this website:
Code:
http://www.useragent.org/
Also, I'm not sure of the exact method your "Bob" guy used, but you can easily ping a computer to see if it is online or not. Most of the time if you are using a DSL or cable connection, you will always be online unless your computer is off.
"Workers of the world unite; you have nothing to lose but your chains." -Karl Marx