From the App-V blog:
For those of you anxiously waiting to get your hands on Microsoft® Application Virtualization (App-V) 4.5 for Terminal Services you'll be happy to know that it will be available to customers as of November 1, 2008 through licensing.microsoft.com. You'll probably see some sort of official announcement on the App-V TechCenter site but for now if you need more details on why App-V for Terminal Services is so cool take a look here.