The developer of YouTube Live has received a notice from Microsoft on behalf of Google asking them to remove YouTube Live, reading:
Remove Application Access Immediately
You must remove access to the application from the Marketplace within one business day. If your application is still available for download after one business day,Microsoft may remove the application without further notice. Please note that under certain circumstances Microsoft may remove your app immediately without providing you the opportunity to remove it."
Google services form a pretty important part of the online experience for most internet users, and it would be pretty damaging if Windows Phone 7 appears not to offer any access to their services. While Google is within their rights to ask for these apps to change their names, it does make it more difficult for new users to find these apps.
At least the notice means Windows Phone has become big enough for Google to take notice, which is not a bad thing in itself.
tl:dr Google doesn't want you using their product names (GVoice, YouTube etc) for third party apps