Dave Simeone, Autodesk Civil 3D Product Manager, stated during today's Civil 3D webcast that it is their intention to make Civil 3D 2007 Service Pack 3 available for downloading today.
With over 100 defect fixes and MANY performance improvements this SP is much anticipated.
I'll post when it is officially available.
PS. The links found in this post allow you to get to the Service Packs Page.