This is an email we just received from WordPress.com:
To celebrate the New Year we’ve decided to offer you more space for your precious media.
Your space upgrade has been increased without any additional cost for you as follows:
5GB -> 10GB
Your total available space has been automatically updated and as you can see in your Media Library.
You now have a total of 13GB.
We hope you’ll enjoy the extra space, and we wish you and your WordPress.com site all the best for 2012!