Yesterday (6 Sept 2011), Adobe labs officially released Flash Player 11 Release Candidate (RC) through this page, some new features that available on Flash Player 11 are :

  • Native 64-bit Support (Flash Player desktop) — Take advantage of native support for 64-bit operating systems and 64-bit web browsers on Linux, Mac OS, and Windows.
  • Asynchronous Bitmap Decoding (new for Flash Player) — Improve app responsiveness and deliver smoother animation by decoding images on initial load instead of on demand. Images are cached as needed.
  • TLS Secure Sockets Support (new for Flash Player) — Enables secure communications for client/server applications.
  • Some other features you can find in here

Download Flash Player 11 RC Ubuntu
Adobe Flash Player 11 RC available for ubuntu and other operating system, you can download Adobe Flash Player 11 through following links
Especially for Ubuntu  64-bit users, you can also upgrade or install Adobe Flash Player 11 RC through this PPA :
sudo apt-add-repository ppa:sevenmachines/flash
sudo apt-get update
sudo apt-get install flashplugin64-installer