The WordPress blogging software tends to stick pretty close to what's available on WordPress.com and the other way around. There are differences though, not just from the fact that one is a hosting service.
There are some features exclusive to WordPress.com, not necessarily because they're "exclusive," but because they require a cloud behind them.
This is where the Jetpack plugin comes in, it packages several cool features from WordPress.com and makes them available to self-hosted WordPress blogs.
The latest update to the Jetpack plugin adds several media gallery features, on top of all that's available with the new media manager in WordPress 3.5. Specifically, it enables users to create photo mosaics and slideshows for their posts.
Jetpack 2.1.1 also comes with updates and improvements to all of its existing features, such as Photon, Infinite Scroll, Publicize, Sharing, and Contact Form. The custom CSS editor has also been updated.
It's not all good news though; there have been some problems with the initial Jetpack 2.1 release and some WordPress 3.5 users have been complaining that the update breaks the media gallery. The bug should have been fixed in the Jetpack 2.1.1 update.
Jetpack 2.1.1 for WordPress is available for download here.