Almost in same period both Virtual Iron and XenSource started their beta programs for upcoming version 4.0 of their virtualization hypervisors.

While Virtual Iron announced pre-opening of Virtual Iron 4.0 beta on July 1st, XenSource is doing so today, detailing some features expected in XenEnterprise 4.0 (and other Xen-based solutions company is offering today):

• Pooled server and storage resources with XenMotion live relocation, enabling dynamic resource management
• Open management integration via the new XenAPI for investment protection for software, skills and processes
• The new XenCenter virtualization management console, delivering more powerful and unified configuration and administration

Registration form and beta bits are available today here.