If you can’t wait to get to tweeting and updating your Facebook page right from your 360, Microsoft is offering players the option to preview the new Dashboard update. Major Nelson updated his blog saying the signup process for preview access has opened and is looking for "multiple thousands" to participate.
If you want to participate and throw your name in the hat, head over to Microsoft Connect and complete the survey. Keep in mind you need a Windows Live ID to participate. If you are selected, you will receive an email in about a week and Microsoft will push the update to your system.