Get Google Apps on your mobile device
Android iPhone BlackBerry Windows Phone  
Options for access
Use your Windows Phone's native apps Set up your Windows Mobile phone with Google Sync to access your Google Apps mail, contacts and calendars from your phone's native applications (requires that your Google Apps administrator enables Google Sync for your domain). Learn more about Google Sync
Use your phone's mobile browser
Access other apps such as Docs and Tasks from your phone's browser app. Just point the browser to, touch the app you want to use, and sign in to your Google Apps account.

What other Google Apps can you use on Windows Phone? Visit Google's Windows Phone Help Center.