Although Microsoft hasn't released a single, authoritative list of the contents of Vista Service Pack 2 (SP2), which will publicly launch as a beta tomorrow, the company has scattered information across its network of sites and bloggers.

Yesterday, Microsoft announced that it had delivered Vista SP2 beta to TechNet and the Microsoft Developer Network (MSDN), its two developer subscription services, and planned to post the 41MB to 90MB download to Windows Update tomorrow for the general public.

The "Notable Changes" document on TechNet lists some of the new features and enhancements slated for Vista SP2. According to TechNet, SP2:

• Supports the 64-bit processor from VIA Technologies ;
• Supports Bluetooth v2.1 delivered by the inclusion of the Vista Feature Pack for Wireless;
• Provides better performance for Wi-Fi connections after the PC comes out of sleep mode;
• Improves performance of the RSS feeds sidebar;
• Supports exFAT, a file system that supports the larger capacity and files used in Flash memory and consumer devices;
• Improves power management efficiency by up to 10 percent on both client PCs and servers;
• Detects incompatible drivers, then blocks installation of the service pack, or warns users of possible problems.

Other additions to Vista delivered by SP2 are spelled out elsewhere, however. For example, Celine Allee, a director in the Windows client IT team, listed several more new features in a post yesterday afternoon to her group's blog. They include that SP2:

Records data on Blu-ray discs; Adds Windows Search 4, the current version of Microsoft's desktop search engine; Microsoft issued Search 4 to Vista users via Windows Update last July as a separate update; Reduces resources required for sidebar gadgets; Cleans up service pack aftereffects and recovers storage space by deleting the previous versions of the files that are updated by SP2.

Later, Allee clarified a mix-up regarding Microsoft's Hyper-V virtualization technology, which is included in the service pack but not installed on Vista machines. "To clarify, Hyper-V is not included in Windows Vista SP2," Allee said. "It is part of the Windows Server 2008 service pack."

The confusion arose because this is the first time that Microsoft has packaged a single service pack that updates both the client and server editions of Windows.

Microsoft has also posted a long list of the bug fixes and security patches that it bundled into Vista SP2. The patches, however, do not include the vulnerability updates that Microsoft released last month, or the emergency patch it pushed to users in late October when it discovered active attacks that exploited a flaw in the Windows Server service.

In other news related to Vista SP2, Microsoft has said it will follow past practice and offer a blocking tool that will let organizations bar machines from receiving SP2 through Windows Update. The company released a similar tool for both Vista SP1 and Windows XP SP3 a year ago that allowed companies to block those service packs for up to a year after their eventual release in March and May 2008, respectively.

Microsoft has not set a ship date for Vista SP2, but yesterday a company executive said that the update was on track for release in the "first half of 2009." Last week, however, a Web site that accurately predicted several Vista and Windows XP ship dates earlier this year claimed that Microsoft would issue a release candidate in February and wrap up work in April 2009.