iMessage for Android users was deep-sixed after Google determined it is a subterfuge to collect user data.

There was a catch in the app, as is discussed by Jay Freeman here. It didn't “make iMessage run on Android”, but rather sent data off for pre-processing to a server in China.

What that meant was users were asked to submit their Apple ID and password to a third party. That's a big no-no for Google. (It's a good idea for anyone that tried the application to run a password reset immediately).

Freeman wrote: “Every packet from Apple is forwarded to 222.77.191.206, which then sends back exactly what data to send to Apple (along with extra packets that I presume tell the client what's happening so it can update its UI). Likewise, if the client wants to send a message, it first talks to the third-party server, which returns what needs to be sent to Apple. The data is re-encrypted as part of this process, but its size is deterministically unaffected.”

Whether the app's behaviors were clumsy or a deliberate attempt to harvest user credentials, it violated Google Play's policies and has been dumped.