Here's info from another tech site:
"What used to be a sole developer hacking iTunes accounts has now sprung into 2 or more developer slash hackers. Thuat Nguyen began hacking accounts to buy his apps numerous times as evidenced by the image above.
Reports are coming in that fraud charges amount anywhere from $100 to above $600. Note that this isn’t AppStore country centralized as users from outside the US are also reporting the incident.
How To Protect Your Account
1.Login to iTunes
2.Change your password to alphanumeric and preferably something above 10 characters
3.Go to My Account > Edit Payment Information
4.Set payment option to NONE
If You’ve Been Hacked Already
1.Email
support@iTunes.com
2.Try and recover your password:
http://iForgot.Apple.com
I suggest you do the following steps immediately as if you wait around, fireworks aren’t the only ones lighting up tonight."
I personally don't use Apple products, so I can't verify the soundness of his recommendations. I'm hearing that Bank of America and Wells Fargo are reporting the fraud so far.