Virtualization has been on a high growth rate for several years. Between 30% to 50% of all servers are now virtualized and there are signs the growth is slowing. The next step is to virtualize the major business applications. Companies have virtualized the low hanging fruit but have delayed on the major applications to mitigate perceived risk. 82% of companies have implemented VMWare, 43% have implemented Microsoft Hyper-V and 33% have implemented Citrix Xen. Clearly there are many organizations with a mix! Microsoft has done a great job gaining ground with Hyper-V because of ease of use, solid features, great price, System Center management integration and a strong user base preferring fewer manufacturers.
Source: “Is Virtualization Hitting the Wall?” by Drew Robb