Google has begun to push out an updated interface to Google Reader users. The new look does away with much of the color seen in previous iterations of the RSS reader, while setting up a foundation for a more streamlined and customizable navigation system.
Part of that navigational change now hinges on small widget-like enclosures, which users can collapse down to take up less space. This is quite similar to what's being done over on iGoogle, and on Gmail to some degree, which could signal the future support for third-party widgets. Considering users can spend hours using the Web app, this could add extra utility, or simply carve out a little more space for ad units.
Each enclosure has its own contextual menu which lets you tweak sorting options on a per-subscription basis. There's also a new option to hide and show the read counts, which will let you feel less guilty if you're coming back to feeds you haven't checked in long time.
Another big change is the automation of feed bundles. Since October of last year, Google has provided groupings of feeds that users can subscribe to at once. These were chosen by Google staffers, which is now a completely automated process done with an algorithm. Google has not said if these feed choices are coming from Google Reader subscription numbers in particular, or from other company properties like search, iGoogle, and the Google toolbar. Nonetheless is means bundles will be faster to update with new feeds. There is, however, not an option to "subscribe" to these bundle feeds to get new recommendations as they're added--something I'm hoping will come in a later release.
If you don't yet have the new interface, just check back later. Out of three of my Google accounts, it's only live on one. Typically Google gets out new features to everyone within about two days.