In August I blogged about the Hosting Deployment Guide for Exchange Server 2010 SP1 Beta, which was really just an incomplete CHM file.
The Microsoft Hosting Partner Technical Advisor Blog has a new post, Hosted Exchange 2010 Migration Guide. Download the ZIP file to get conceptual architecture, migration overview, migration guidance, HMC specific migration guidance and sample scripts to support your move to an Exchange 2010 SP1 Hosting forest.
You have a few standard requirements and limitations, but you will have to upgrade your control panel or services behind it. You may choose in house development, or join the increasing numbers of hosting providers outsourcing control panels to Ensim or Parallels.