Rick has just posted this information over on the CanITPro blog (http://blogs.technet.com/canitpro/archive/2006/02/27/420707.aspx)
For business users, we are going to be releasing two different versions of Vista: Windows Vista Business and Window Vista Enterprise.
For your use at home, we are going to be releasing three different versions: Windows Vista Home Basic, Windows Vista Home Premium and Windows Vista Ultimate.
Rick has a more detailed breakdown of what is in each version, so head over to his post to check it out.
If you are looking for more technical information for your staff, check out the new TechNet page for Vista.