Andrew,
today SPS and SBS do not sit well together becasue SPS & Exchange are strongly advised to not run on the same box.
Given the timeframe until SBS LH - which is post Longhorn, which is 2007, anything is possible, but I would be more interested in the features they are after - it is possible that the Office 2007 versions (Windows Sharepoint Services V3) and Longhorn might do what they want, so could you give me an idea of features of scenarios you are trying to solve?
thanks
David
(c)David Overton 2006-23