According to the Microsoft Press site beta version of  Windows XP Mode will be made available on April 30.Windows XP mode allows users of Windows 7 Professional and above to launch many older Windows XP productivity applications directly from their Windows 7 desktop. The Windows XP Mode stand-alone feature is specifically designed to help small businesses that are using Windows XP applications move to Windows 7. For larger businesses, Microsoft Enterprise Desktop Virtualization (MED-V) MED-V 2.0 builds on top of Windows Virtual PC and provides centralized management of Windows XP Mode. MED-V 2.0 will be available in beta within 90 days of general availability of Windows 7.

Here is what the Microsoft Press pass reads

We are announcing the beta release of Windows XP Mode for Windows 7. Small businesses told us they wanted help upgrading to Windows 7. Windows XP Mode, an optional feature of Windows 7 Professional, Enterprise and Ultimate editions, helps small businesses upgrade to Windows 7 by providing a virtual Windows XP environment capable of running many Windows XP-compatible business and productivity applications. Customers can run many older Windows XP business and productivity applications within Windows XP Mode and launch them from the Windows 7 desktop with just a single click. A beta of Windows XP Mode will be made available on April 30.

We would be posting more information as and when it is available