The latest addition is Virtual Server 2005 R2. Microsoft officials announced at the Intel Developer Forum this week that they had decided to christen the first service pack update for Microsofts Virtual Server 2005 product as an R2 release instead of SP1.
The renamed product is still due to ship in the fourth quarter of this year.
Other products for which Microsoft is releasing R2 interim updates include Windows Server 2003 R2; Small Business Server 2003 R2; and Speech Server 2004 R2.
Virtual Server, which is based on technology Microsoft acquired from Connectix Corp. in 2003, allows customers to run multiple operating systems, including Linux and Unix, concurrently on a single x86 hardware server.
Microsoft officials have talked up plans for Virtual Server 2005 SP1 for months. The primary enhancements were the addition of x64-based system support and support for Linux as a guest operating system. Microsoft released a first SP1 beta in April.
Microsoft officials also said the company was planning to release a Virtual Server "Version 2" product in 2006. On Wednesday of this week, officials reiterated Microsofts plans to field a follow-on to Virtual Server 2005 R2 (which has yet to be named) in the latter half of 2006.