One almost surefire way to find if a new feature is on the verge of launching is to dig through code. That’s exactly what led to finding a reference to something called “Magic Inbox,” in Gmail. But what is it? Well, it could just be another one of those nifty, but small new features that Google loves to roll out in Gmail Labs at breakneck speed. But there’s a chance it’s something much, much bigger.Specifically, Google Operating System, which did the digging, believes that the feature likely is a way to sort your Gmail inbox by your social graph. The two references to “friends” in the code, seems to lend some credence to this. Presumably, this would allow you to better filter your inbox based on if you have specified the emailer as a contact. As someone who gets bombarded by email everyday, most of which is not from people I actually know, I would weep with joy if such a feature were implemented. And so would my mom, as she may actually get emails back from me were that the case.Of course, others have been working on this same idea as well. Yahoo has been saying for a while that it wants to use your inbox as a part of your social graph. Microsoft’s Hotmail has been working on things in the area as well, as has Xobni. But given all the work Google has been doing recently to tighten up its social graph across its huge network of services, a social filter in Gmail could be very, very useful.Users are likely to have security concerns about this as well. Some people want their email client to be completely private and not a part of the social graph. Of course, Google has already been using Gmail as a key starting point for your social graph for a while now, even if you didn’t realize it. Well over a year ago, Google it rolled out its social features to Google Reader, pulling in who it thought your friends were based on who you emailed in Gmail.This proved to be an awful idea as people you email aren’t necessarily your friends. Google eventually rolled out several updates to this feature to