tcar, I'd say that "generally", based upon the routed IP address (think of it as an area code/phone #), one can identify the poster's "location" and reach a conclusion that it was indeed the same person. Can it be "hidden from view", translated, or made VERY complex to track - yes, but the short answer to your question would still be yes.

tcar - maybe yes, maybe no. When I post from work, it will come from one of 2 or 3 addresses, depending on what building I'm in - of course, there is the possibility of 5,000 folks using those same external addresses at the same time too, but I think I'm the only one that posts here from them (I do send links, esp. the random pix thread to coworkers). Those addresses haven't changed in years. A leased line would be similar - no change in years. Cable and DSL connections will tend to change at least once in a while, if not frequently (my home DSL IP changes a few times a day on its own, more when I have to reboot my POS "modem" and/or router). A business class DSL or cable connection will probably keep the same IP for "forever" as well.

So, if a mod/Wayne looked at a history of this persons posting, and the one address was consistient, and a new account is using that address then yes, it is likely the same person - but no guaranteed to be.