Google will no longer support new Exchange ActiveSync connections from Windows 8 PCs and tablets to sync Gmail, Google calendar and contacts from Gmail after January 30th, 2013 If you've already connected your Google account to your PC running Windows 8 and Windows RT using the Mail, People or Calendar apps, you don't have to do anything. Existing EAS connections to Google accounts will continue to function.
If you are trying to connect a Google account after January 30th, 2013 to your PC running Windows 8 and Windows RT using the Mail, People or Calendar apps, please visit this support article.
The worst news is that Google has no plans to release Gmail and other Google apps for Windows 8 and Windows Phone 8.