Without getting into the background issue of WHS losing its best feature, Drive Extender, here is a fix provided by Microsoft to extend the current WHS Vail beta until the new Drive Extenderless Beta bits gets published in the short term.

“Today the WHS beta expires, and as such moves into Windows Server 2008 R2 Expiry mode (where the server will reboot hourly).  It is important to note that – No data is lost during an expiry, and users will still be able to access the server if needed to.

“The beta is built on an evaluation copy of Windows Server 2008 R2, where the eval expiry is hard coded during beta development (and as such cannot be easily changed).  However working with our engineering team, there is now a workaround using Windows Server 2008 R2 SP1 RC.  This will extend the expiry to mid-March.

“To extend the expiry, please follow the directions below

1.    Install WS08 R2 SP1 RC on the server from http://www.microsoft.com/downloads/en/details.aspx?familyId=c3202ce6-4056-4059-8a1b-3a9b77cdfdda&hash=2SduI20oa3rGcMvoU%2bPV1TVHUik%2f3CNeLRmMuOcJXzz13kgszkD2VWTIpb%2bAS0in9K12Sc14FpC3sdT4PNXCUw%3d%3d
2.    Logon on https://connect.microsoft.com/WindowsHomeServer with your connect credentials
3.    Click on Product keys (in the left hand side column)
4.    Click on Request a new product key
5.    Click on Get Key
6.    In Windows Home Server, open a command prompt
7.    Type “slmgr.vbs -ipk ABCDE-FGHIJ-KLMNO-PQRST-UVWXY” (where ABCDE.. is your new key as requested above)
8.    Type “slmgr.vbs –ato”
9.    Reboot the server, and your beta timeframe has been extended.  You can check this by opening up a command prompt and typing winver

Many thanks to Mary Jo Foley for the info.