I was just curious what an IP meant - whether one's posts can be traced using this and who actually has access to it?

Okay, I got this from Wikipedia, since I would never be able to explain it properly:

IP address

An IP address (Internet Protocol address) is a unique* number that devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP). Any participating network device — including routers, computers, time-servers, printers, internet fax machines, and some telephones — must have its own unique address.

An IP address can also be thought of as the equivalent of a street address or a phone number (compare: VOIP) for a computer or other network device on the internet. Just as each street address and phone number uniquely identifies a building or telephone, an IP address can uniquely identify a specific computer or other network device on a network.

An IP address can appear to be shared by multiple client devices either because they are part of a shared hosting web server environment or because a proxy server (e.g. an ISP or anonymizer service) acts as an intermediary agent on behalf of its customers, in which case the real originating IP addresses might be hidden from the server receiving a request. The analogy to telephone systems would be the use of predial numbers (proxy) and extensions (shared).

... The adminstrators are able to view each member's individual IP address, but cannot use it to trace or search for your posts.

Hmm... That was quite the interesting read...