Ms finished the Sp1 in November. The Buildnumber is 7601.17514.win7sp1_rtm.101119-1850. I saw this because the first hotfixes are out which apply to Windows 7 RTM and Sp1. The request page also states SP2 as milestone.

Now lets wait for the Release and the integrated ISOs to be released on Technet/MSDN.

Later edit:

Microsoft released the Update KB976902 on WindowsUpdate which is needed to install the Sp1. It also proves that Windows 7 Sp1 is done and the version number is:

6.1.7601.17514 (win7sp1_rtm.101119-1850)

ive never been happier with any other version of the windows before and its odd to say that im actualy happy about the 7 already. well i guess sp1 will just make it better.

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first security updates for Sp1 are released on Windows Update

yes I allready have sp1x64 for 2+/-, weeks now it works perfect even i didnt make clean install. it is not leaked version -its from microsoft

from mic.- info about sp1

We are pleased to announce that subscribers to on-line resource TechNet / MSDN from February 15, 2011 will be available for download the first service pack SP1 for Windows 7/Server 2008 R2, and c 22 February 2011, Microsoft will provide an opportunity to download SP1 for Windows 7 / Server 2008 R2 and all other interested persons.

Of course everyone will see the assembly 7601.17514.101119-1850.

PS: about the future plans of the corporation, we reported separately.

Today we officially handed off the final release (RTM) of Windows 7 and Windows Server 2008 R2 Service Pack 1 (SP1) to our OEM partners. On February 16th Windows 7 and Windows Server 2008 R2 SP1 will be available for MSDN and TechNet Subscribers as well as Volume License customers. On February 22nd, Windows 7 and Windows Server 2008 R2 SP1 will become generally available for folks to download via the Microsoft Download Center and available on Windows Update.

For Windows 7, SP1 will help keep your PCs well supported by delivering ongoing updates, many of which have been made previously available through Windows Update. It also includes client-side support for RemoteFX and Dynamic Memory which are two new virtualization features enabled in Windows Server 2008 R2 SP1. Read more about those updates here from the Windows Server Team.

http://windowsteamblog.com/windows/b/bloggingwindows/archive/2011/02/09/announcing-availability-of-windows-7-and-windows-server-2008-r2-sp1.aspx