User blog comment:DaNASCAT/Technical Update: March 20, 2012/@comment-1513877-20120324033637/@comment-3508190-20120327030520

Okay, okay. IE10 is not official yet. It's just a preview version.

And you're right about Chrome and Safari. They too show the gradients. I stand corrected. Then why do I only see -moz prefixed properties in the source?

I guess FF silently drops the properties it doesn't understand...