Quoting from the Stratus official announcement:
Stratus Technologies, Inc. announced today its membership in the VMware Community Source program, which enables Stratus to collaborate on highly available and reliable virtualization solutions. The program provides Stratus and other vendors with the opportunity to work with VMware on VMware ESX Server source code development and product direction under a royalty-free license.
…
The Stratus ftServer server family of Intel Xeon processor-based systems supports both the Windows and Red Hat Linux operating systems. Pricing begins as low as US$10,000. Systems are highly configurable to support a broad range of business requirements, application types and workloads. Field-proven uptime reliability for ftServer systems consistently exceeds 99.999 percent…
Stratus ftServers are manifactured by NEC which redistributes them in parallel under the name of Express5800 FT.
Both NEC and Stratus yesterday announced quad-core versions of their fault tolerant servers, which will be available in June.