On the 3D front, Adobe's improved its stereoscopic 3D workflow by simplifying the setup of the dual-camera rigs needed for capturing and rendering 3D video and adding an updated 3D Glasses effect. Camera Lens Blur will also let you quickly add some impressive soft-focus and depth-of-field blur effects to the After Effects 3D camera, giving you control over the iris shape, blade curvature and diffraction characteristics.
After Effects C5.5 also comes with improved organizational support for source timecodes. It'll now read and display timecode data directly from the source file in several different formats, and it will integrate it with a customizable Timecode Effect, showing both the source timecode and composition frames.
Adobe's also spent some time on optimizing the memory footprint of After Effects itself, with better disk caching and default memory settings for improved performance. Raw digital camera import has been expanded as well, with greater support for RED and CinemaDNG import, plus the addition of XDCAM EX and HD output.
Finally, just as with other program upgrades in the CS family (like InDesign), support has been added for backwards compatible saving for pre-CS5.5 versions. That's bad news if you happen to be working with someone else who's unlikely to upgrade anytime soon, because you're going to have to specially export it every time you want them to be able to work on it, but at least you have the option. It's also important to note that, like its predecessor, After Effects CS5.5 requires a 64-bit Leopard 10.5.8 or Snow Leopard 10.6+ install running on a multi-core Intel processor to run. But if you're trying to do any serious video editing, you'll likely be running a machine that's less than two to three years old anyway.
After Effects CS5.5, along with the rest of the CS5.5 suite, is available for pre-order right now. Trial and purchase options will be available soon, including a US$49 per month subscription that nets you the $999 app for less than $600 a year. If you're still not convinced by that and want more information, head on over to the After Effects CS5.5 site for the full skinny.