Vista SP1 was released to manufacturing today 2-4-08 Expect to see a customer release in early March.

From Microsoft:
Windows Vista Service Pack 1 (SP1) was released to manufacturing today and will start being available to customers in March, starting with Microsoft Volume Licensing customers. Windows Vista SP1 includes quality improvements that help enhance reliability, security and performance. SP1 also includes changes focused on improving the performance of Windows Vista in areas that impact the customer experience the most.  For instance, with SP1, copying or moving files around your PC, your home network or your corporate network should now be much faster — up to 50% faster in some scenarios (according to our internal tests).  In addition, on many kinds of hardware, resuming a Windows Vista-based PC from sleep is faster on Service Pack 1.

Here’s the timing for SP1 availability for current Windows Vista users:

In mid-March, we will release Windows Vista SP1 to Windows Update (in English, French, Spanish, German and Japanese) and to the download center on microsoft.com.  Customers who visit Windows Update can choose to install Service Pack 1.  If Windows Update determines that the system has one of the drivers we know to be problematic, then Windows Update will not offer SP1.  Since we know that some customers may want to update to SP1 anyhow, the download center will allow anyone who wants to install SP1 to do so.

In mid-April, we will begin delivering Windows Vista SP1 to Windows Vista customers who have chosen to have updates downloaded automatically.  That said, any system that Windows Update determines has a driver known to not update successfully will not get SP1 automatically.  As updates for these drivers become available, they will be installed automatically by Windows Update, which will unblock these systems from getting Service Pack 1.  The result is that more and more systems will automatically get SP1, but only when we are confident they will have a good experience.
The remaining languages will RTM in April.