Update: Google has pulled the iMessage Chat app from the Play store, confirming to ComputerWorld it had done so because the offending app violated the store's policies.
Apple's iMessage messaging platform allows users of iOS and Mac devices to exchange text, pictures and other documents free of charge via a data connection. The service uses Apple's servers with the users' phone numbers and email IDs to process messages through the Messages app, and the closed service is restricted to only Apple devices.
However, a new app called iMessage Chat claims to bring the service to the Android platform allowing users to exchange messages with Apple's devices. Even the look and feel of the app is in line with the design of iOS apps(pre-iOS7). It was first spotted by 9to5Mac.
The app has not been developed by Apple but by a third-party developer named Daniel Zweigart.
Developer Adam Ball notes that the app disguises itself as a Mac mini to connect to Apple servers.
So it looks like that iMessage on Android hack is super sketch and is spoofing iMessage requests as a mac mini: pic.twitter.com/TYT6Djumdv-- Adam Bell (@b3ll) September 24, 2013
A number of users claim that they have been able to exchange messages between Android and iOS devices.
It's worth pointing out that the app asks for the user's Apple ID credentials and messages are processed through a server in China, as noted by Jay Freeman, creator of Cydia.
Note: So the developer could store and access your Apple ID and all the messages exchanged through the app. If you've linked a payment method with the Apple ID, it could be misused to download apps and content or just block you out of it.
Another developer, Steven Troughton-Smith tweeted that the iMessage Chat app is capable of downloading and installing other apps (via app APK files) in the background. This means that it could offer a backdoor entry to spyware and malware apps putting your phone into risk.
Bottom Line: It's not advisable to download and install this app as it could turn out to be a security and privacy threat. If you're still feeling adventurous you can try creating a new Apple ID and try the service logging in with the same.
Cross-platform apps like WhatsApp, Google Hangouts, WeChat and Line offer similar functionality and are much more secure and don't ask for an Apple ID. So, it's better to stick with them.