The general consensus seems to be that this is one Bad piece of malware. Just Google it and you'll find a lot of references starting earlier this month. Bleeping Computer has several threads regarding the infection and it looks like, while it's apparently easy to rid yourself of the actual infecting malware, once it has done it's job your files will remain encrypted and unusable.
It seems for the most part, at least here in the U.S. the attack vector has come by way of email attachments masquerading as email for the United States Postal Service. So if you receive any unexpected email from the Postal Service, Post Office, Post Master, Post Master General or the USPS that include an attachment, you'll likely want to avoid them.
Generally speaking, email with attachments that you are not expecting, even from formerly, known, reliable sources should still be avoided unless you can otherwise confirm their respective legitimacy with the actual sender.
In some instances, some people have reported, some success in recovering earlier versions of the encrypted files, courtesy of the Volume Shadow Copy Services and a small program called Shadow Explorer.
Anyhow, forewarned is forearmed so I thought I would pass this along.