Microsoft partnered with Adobe with optimize Flash for touch, performance, security, reliability, and battery life. Battery life is probably one of the biggest points for optimization. However, the update does have a catch. Websites that are on Microsoft's compatibility view list won't be able to run flash, because the site(s) in question are not optimized for touch, or depend on other plugins.
In the table below, this is how flash will be "turned on" by default:
|Windows 8||Windows RT|
|Immersive IE||Enabled unless on CV list||Enabled unless on CV list|
|Desktop IE||Enabled on all sites||Enabled unless on CV list|
A few weeks back, Internet Explorer 10 was released for Windows 7, stable. That update brought along more standards support and more features.