But, how useful would seeing; IP-195.168.1.555(yes I know it's not valid...) bought coffee, some socks, sent a few random IP's BTC and sent some BTC to MtGox really be? I think the main thing to take away here is that both torrent and BTC reports would only work on users who did not know how to anonymize themselves properly. Anyone who cares enough to not have their internet usage tracked should be making that their first step.
A huge part of the appeal of bitcoin is its ability to be mostly hidden from being traceable to the owners of coins. You may buy btc for very mundane things, but a large segment of bitcoin users have a reason to keep their purchases private.
aye, and those people should know how to be anonymous. My inclusion of 'a few random IPs' was meant to include people that are sending/receiving to places unknown. And was not a list of what I use it for. Though I have no desire to use it for anything illegal, I can certainly appreciate someone's desire to not have their purchases known. I happen to service some of those entities now with USD.
But, that doesn't really answer your question. It's been said many, many times though that bitcoin by itself is not completely anonymous. Yes, it would be possible for someone to aggregate all the IP information associated with transactions.
