Barely after ten days, Microsoft released the SP1 RC-Escrow (build 7601.1701.1704) to testers, the build has been leaked to the internet. Several underground forums, reporting that the Windows 7 SP1 RC-Escrow build is now available to download via file sharing sites.
The build string is 7601.17104.100921-1630, which indicates that the current build was compiled on 21st September at 4.30 PM.
At this point, it appears that only x86 version has surfaced and certain sites are also reporting that the leak is actually a pre-RC build and not the genuine article.
If the unofficial sources are to be believed, the official RC build will be released on 26th October.