I know you all want ice cream, but you'll just have to wait. Everyone on a Epic 4G has what appears to be a test build (better than nothing!) of the Android 2.2 Froyo OS build available to them today on an official tip from Google themselves. Have a peekie at it if you do so dare. [ZIP file] Instructions on what to do with this sweet junk are available via the excellent pack of magicians over at XDA.
Head over to the XDA Developers Forum thread and figure out what you've got to do with the contents of the ZIP file, and have yourself a taste of the sweet stuff. Tell them we love the way they rock and roll with their sweet developer guitars, rock and roll so hard.
[Via XDA Developers Forum]
Update: Sprint's advice is to not install this test update; there's no confirmation that if you load the ROM you'll then be able to install the official Froyo firmware when that's released.