The hacker group Lulz Security claimed that it had obtained login information for about 62,000 private internet accounts a few days ago from different sites, including Facebook, PayPal, some dating sites, Xbox Live and Twitter.
They have been uploading the file contain the credentials to these accounts to file sharing sites. A lot of these accounts have been accessed by others using these credentials. After logging in, they have been changing the profile photos, changing passwords, using the chat services, transferring money out of these accounts, etc.
If you want to know if your account has been compromised, you can check at Dazzlepod. They have provided a search feature. When you use it, make sure that you only enter part of your email id and not in full. You may get a bunch of results that match, but that will certainly be a much smaller subset.
Another reason passwords should never be stored in clear text by any website.