One of the unseen bonuses to the upcoming Xbox 360 dash update is the downsizing of install sizes. Two examples, dug up by people who pay a lot of attention to this stuff, include King of Fighter XII and Raiden Fighters Aces. Their install sizes used to 3.4GB each, and have now been downgraded to a (much) slimmer 703 and 484MB each. Other games, such as Fable II, have zero benefit in the updated dashboard.
No word on why the change happened, and Microsoft never made it known this would be the case. Thanks to the preview program which let some users in early, this was found prior to the release.