Via GIGAOM
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Google is working on new APIs to support something called
“copresence,” but what it might be isn’t yet clear. A tip from the blog
TechAeris suggests a new cross-platform messaging system between Android and iOS, which is certainly plausible. I did a little digging in the Chromium bug tracker and found 18 mentions of copresence there, along with a pair of related APIs available on the Chrome dev channel.

Here are all of the bug listings, all of which were at least updated this month, meaning that Google has been pretty active of late on copresence. Scanning though these I saw one mention of GCM, which is the Google Cloud Messaging service that’s already available to Android app makers. Developers can deliver files or data from a server to their respective Android app through GCM.
But the TechAeris report suggests copresence will do more than what
GCM does today. Based on a source that scanned the latest Google Play
Services build, numerous references to copresence were found along with
images alluding to peer-to-peer file transfers, similar to how Apple’s
AirDrop works between iOS and OS X. One of the images in the software
appears to be song sharing between an iPhone and an Android device.

Copresence could even be location-based, where the appropriate app
could tell you when other friends are nearby and in range for transfers
or direct communications. Obviously, without an official Google
announcement we don’t know what this project is about. All of the
evidence so far suggests, however, that a new cross-platform
communication method is in the works.
Update: In a review of the Google Play Services software last month, Android Police noticed the copresence mentions that may correspond to a Google service called Nearby.