On his blog, Biplab Paul, a Technical Consultant at Microsoft revealed the final Vista Service Pack 1 release schedule:
When will SP1 be shipped?
- Mile Stone 1 (Feb 4, 2008): Available to OEM and Retail Channel
- Mile Stone 2 (Early March 2008): Vista SP1 Volume Licensing Availability
- Mile Stone 3 (Mid March 2008): Vista SP1 availability through Windows Update/MSDN/TechNet
- Mile Stone 4 (April 2008): Will be pushed via Automatic Update