According to Adobe's website, Adobe Reader has recently been updated, from version 8.0 to 8.1. A changelog is not available yet.
Adobe's description of Adobe Reader:
*Work smarter - a clean new look, custom toolbars and an RSS reader
*Work faster - 2D acceleration (requires video card support, Win only)
*Work together - new online conferencing with Acrobat Connect
*The ONLY Reader that can open and view all PDF files with full functionality
News source: Source & Download