MobilityDigest has mentioned a neat tip for group messaging on Windows Phone Mango which others may find helpful. When making a group, e.g. for collective Facebook updates or messaging, one does not actually have to go to the group Live Tile to share info. The group can be accessed directly from the address bar in the messaging client simply by typing in the name e.g Family.
That means sharing a webpage to a group of friends would be as easy as going to the sharing menu item in IE, choosing Messaging and typing in Friends.
Thanks MobilityDigest for the tip.