Your IP address, local date/time, browser details, etc are sent to every single webpage you view, or email that has a graphic in it (hence why hotmail now doesn't display graphics unless you set it up to).
The member Trubster has just a graphic in his signature and your IP details are displayed only to you. No other forum member can see your IP details unless a moderator/admin.
For example, I see my IP address on his signature and the fact that I'm using IE7.
In fact, more information than you realise is sent to every single webpage you visit. Visit
this page and scroll down and see what information can be collected by just simply visiting a webpage.
The signature graphic as shown by Trubster is from
www.danasoft.com.