It’s here. Windows 7 SP1 is now available for download through Windows Update. This is what your download Window will look like if you expand the view of Important Updates inside the WU interface:
The blurb says it will take about half an hour to install, but my own experience so far has been more like 12 to 20 minutes, depending on CPU and hard disk channel speeds. Those who’d rather download an ISO image or an installer file can now do so through the Microsoft Download Center, if they prefer that to Windows Upate. Look for the DVD .ISO image (this is what I downloaded and burned from MSDN last week, because it includes both 32- and 64-bit versions of the Service Pack), or separate 32- and 64-bit installer files. You must install Windows Update KB2454826 before you can install Windows 7 SP1, but if you’ve been installing incoming updates anyway you should be OK, because this hit Windows Update several weeks ago.