Yes, it will be compatible with Windows 7. There would be a massive backlash if this game didn't work on Win7. Because Win7 is pretty much the standard operating system for PC currently, it would almost be a lie to say that the game is coming out for PC if it didn't work with Windows 7.
A lot of the PC games on Amazon have only a few versions of Windows listed instead of all of the compatible versions. For instance, GTA IV only has Windows XP listed, but I can play it on my Windows 7 computer. Dragon Age Origins is listed as XP/Vista, and it runs fine too. I'm not sure why Amazon does not have all of the Windows versions listed, but you can be fairly confident that any modern PC game will be compatible with Windows 7.
Windows 7 and Vista have different product names, but they are the same OS in terms of application compatibility. Windows Vista internal version number is 6.0, Windows 7 is 6.1. That's considered a minor version upgrade.