The Verge reports Google dropped a small bomb on Microsoft by announcing that it's removing support for Microsoft's Exchange ActiveSync protocol for new devices from January 30th, 2013. As a replacement, Google recommends CalDAV for calendar, CardDAV for contacts and IMAP for e-mail, but the Windows Phone platform doesn't support CalDAV nor CardDAV, and the e-mail only option is an IMAP connection without push support. At present, it's unknown if Microsoft plans to resolve the issue by adding support for CalDAV and CardDAV to its Windows Phone platform.
For iOS, Google's email solution is IMAP support and a dedicated Gmail app, CalDAV for calendar, and CardDAV for contacts. Apple and Google both support CalDAV and CardDAV natively, but Microsoft has chosen not to support either standard in Windows Phone 8… yet. This leaves Windows Phone users in a tricky position: at present, they’re offered two choices to set up a Google account. You can pick between email only or a combination of email, calendar, and contacts. The email-only option will set up an IMAP connection to Gmail which won't support push — it’ll sync every 15 minutes at best. The second option with calendar and contacts lets Windows Phone 8 users setup a Gmail connection using Exchange ActiveSync, with push email, calendars, and contacts. This solution will cease working from January 30th for new devices, leaving Microsoft little over a month to provide an acceptable alternative for end users.
Google is not providing a Gmail app for Windows Phone users, and the company recently revealed it has "no plans to build out Windows apps" beyond a search app available on Windows 8 and Windows Phone. "We are very careful about where we invest and will go where the users are but they are not on Windows Phone or Windows 8," says Google Apps product management director Clay Bavor. Meanwhile, Apple's situation is fine for iOS users as the company hasn’t opted to use Exchange ActiveSync by default and CalDAV and CardDAV are both supported natively.