"The next version of Adobe Flash Player will offer a variety     of new features and enhancements as well as some changes to the current     behavior of Flash Player. Some of these changes may require existing content to     be updated to comply with stricter security rules. Other changes introduce new     abilities that were previously unavailable or restricted by security rules.

Please review the following security-related changes being     made to Flash Player 10 beta. Use this list to determine whether you will need     to make changes to your existing content for it to function correctly in the     next Flash Player release.

Changes that may require action

• Policy file strictness: Phase 2
• Socket connection timeout
• Upload and download require user interaction

New security-related features that are available

• Local save and load
• Limited full-screen keyboard input
• Peer-to-peer communication via RTMFP"

Article: http://www.adobe.com/devnet/flashplayer/articles/fplayer10_security_changes.html