Why anyone would do this remains a mystery. Is it just some sort of publicity stunt, or a hacker's brag?
eBay shut down the forum and pulled the pages about an hour after being informed of the incident. There's more about the incident on an eBay blog.
"eBay spokesperson Nichola Sharpe said Tuesday afternoon that posts made on the Trust & Safety board early this morning contained name and contact information for 1,200 eBay members and called the person posting the information a "malicious fraudster." She said the incident was not the result of a security breach from eBay and could have been obtained as part of an account takeover."
It's possoble that a merchant's account may have been compromised, I guess.