If you signed onto Xbox LIVE yesterday, you were probably forced to download a new dashboard update before you could sign in. Major Nelson wrote on his blog that this mandatory update re-added the "Boot to Disc" option that was erroneously removed in a prior update. Enabling this feature will allow you to directly launch into the game in your disc tray rather when you start up your console rather than having to go through the Xbox 360 dashboard and hit "play".
As you might have noticed, the update took forever to download. It took a lot longer than would be expected if it was simply restoring a previous feature. It's being reported that Microsoft also secretly beefed up their anti-piracy security with this update by blocking the use of flashed firmware disc drive modifications. Many users on gaming forums reported that their modded copies of Call of Duty: Black Ops immediately stopped working after the update. Trying to get around this new block has resulted in some gamers being banned from Xbox LIVE.
This is a good move by Microsoft following the recent PS3 jailbreak. It shows that Microsoft is still cracking down on software pirates which will give developers confidence that their products can continue to find a safe home on the Xbox 360 console.