That's an excellent question, Hal. I read on TechSoup that the software can be used for Terminal Services.
TechSoup:Small Business Server 2008 Premium Edition includes an additional copy of Windows Server 2008 to optionally run on a second hardware server supporting line-of-business (LOB) applications, and this edition can now also be used for Terminal Services access to applications.
However, I believe that was referring to the Windows Server 2008 Standard license that is given for the second piece of hardware in the SBS 2008 Premium. I think that means that since it is a full version of Windows Server 2008, instead of a reduced set of functionality in Windows Server 2008 Technologies on the first server, then you could technically use it for Terminal Services.
However, nowhere in the description of SBS 2008 Premium Server or the Device/User CAL descriptions do I see any mention of it granting you access to Terminal Services. Nor did I ever see Terminal Services mentioned in the list of features on the Microsoft site for SBS 2008. Microsoft also says the Line of Business second hardware server is a full version of Windows Server 2008 Standard.
So, in SBS 2003, Standard or Premium, in order to use Terminal Services, you had to install a separate member server and buy a full version of Windows Server 2003 and Terminal Server licenses. I think the only benefit of SBS 2008 Premium is that you have the full version of windows already installed on a second piece of hardware, so its not necessary to purchase these additional licenses - except ther CALs for Terminal Server.
It's an educated guess on my part that you'll still need to purchase Terminal Server licenses for your devices if you get SBS 2008 Premium Edition.