Google has pushed out some updates for its Sync capabilities on Windows Phone Mango devices. Previously a user was not able to access more than one Calendar at a time when syncing a Google account on a Mango phone, but now by going to http://m.google.com/sync you can select up to 25 calendars to sync to your device.
Another nice improvement is the ability to choose which account to reply from if there are multiple SMTP accounts configured in your Gmail settings.
Gmail search has also been tweaked to search beyond the allotted 25, 50 or 100 local emails in your Gmail inbox to all your emails stored on the server. Very convenient.