A Twitter user @WindowsPhone8 tweeted about the new feature of Microsoft's next major update to its Windows Phone platform codenamed "Mango":
#WP7 mango has a new email "linked inbox" and it's better than a unified inbox
"Linked Inbox" is rumored to be an improvement over the universal inbox technique used by Apple with the iPhone. It seems most likely that the Linked Inbox capability will allow users to group together specific email accounts into a single inbox - but may also provide the flexibility of keeping other inbox accounts separate. And in each, case it's anticipated email inboxes of both varieties could be pinned to the home screen in typical WP7 style (as is the case with email inboxes on WP7 today).
The other minor feature is a small change to the Live Tile for the people hub. It appears Mango will now mingle large and small pictures of people on this Live Tile. The images are randomly drawn from images of each user's contacts and friends - whether they are from Facebook, Exchange or a Windows Live account (or no doubt Skype in the future).