From what I've read SnapDrive 6.0 will support this. Unfortunately, we have rules about talking about release dates in public. Your sales team can discuss these things with you under NDA. But I think I can safely say "very soon"
That is a safe statement. SME 5.0 wil require SDW 6.0 for Windows Server 2008 support. And yes, SME 5.0 will support Exchange 2007 SP1. SME 4.0 also supports Exchange 2007 SP1...but on a Windows Server 2003 platform.