Google Talk mobile app service will not work now, Google has shut down the mobile app services. Android users need not worry as these services will affect iOS and other users who are using a 3rd party app to communicate with Google Talk.
According to Google, users will still be able to access Google Talk via native apps, as in the case of android smartphones (Google Talk App). The users who are using Apple smartphones or 3rd party apps will not be able to access the Talk services; however 3rd party app with XMPP compliant methods can still access the Gtalk services.
Almost all of the android phones come with host of Google services including Google Talk. The Micromax A90 that I recently bought did not have the Google Talk apps, but I got access to the APK file which seems to be working fine.
It seems Google will slowly remove the talk services and replaced it with something better, something new, probably integrated with Google+ services. Google did mention that they are working on some exciting updates, something new, something futuristic, so watch out.
All users who are using a 3rd party app on your mobile phone, logged on to Google Talk, you might want to start looking for an alternative.