Serious business: check this article on uk.playstation.com and log into the PSN as soon as you can to ensure that your account has not been breached – looks like passwords have been changed and purchases made with wallet contents, albeit on a minor scale.
This could be linked to a spam PSN message circulating recently: never give out your password, even to a Sony rep, as they’ll never ask you for it.
Update: additional link here for those using non-standard browsers, like IE. ;)