Why not Beta 2? we have Beta1 nearly a year now...

Beta 1 Versions
Since releasing Windows AntiSpyware (Beta) on January 6, 2005 (Build 1.0.501), we have continued to receive feedback from customers. We introduced a beta refresh on February 16, 2005 (Build 1.0.509) which enhanced some of the real-time protection agents, added new threat categories, and improved stability and performance.

An updated beta refresh released on June 23, 2005 (Build 1.0.613), introduced enhancements to the detection and removal capabilities, including improved Winsock LSP removal capabilities and support for long descriptions of categorized software. In addition, we have also extended the Windows AntiSpyware beta expiration date to December 31, 2005.

An updated beta refresh released on July 18, 2005 (Build 1.0.615), addresses issues pertaining to how Windows AntiSpyware (Beta) provides information to the user about processes running on a PC, solves an issue regarding the delivery of new anti-spyware signatures for some customers.

The latest beta refresh, build 1.0.701, extends the Windows AntiSpyware beta expiration date to July 31, 2006 and provides new signature updates to help protect against recently identified spyware.

Existing users of the beta (Build 1.0.615) will receive a software update that includes the new beta refresh. The latest beta refresh is also available for download through this site.

Microsoft would like to encourage all Windows AntiSpyware (beta) users to download and install the new update (Build 1.0.701). Download At Source