Google revealed this month it's plans to not to release Google apps, like Gmail, Talk and Drive for Windows Phone and Windows 8. And from January 30, Google is pulling support for the Exchange Activesync protocol, which means Windows Phone users won't be able to sync contacts and calendar events. For receiving and sending Gmail, they will have to use IMAP which is an old technology and don't support push email.
Apple iPhone and iPad users won't be affected because there is a native Gmail app for iOS. If you want Google to release Gmail and related apps for Windows Phone and Windows 8 then sign this petition.
Remember, it's not Google strategical decision to not to support operating system made by a competitor. In an interview, the director of Google Apps, Clay Bavor, said that Google is not working on apps for Windows devices due to lack of interest from its clients on the systems. So if you will take some interest and sign the petition, it can really make a difference.