Update: Google's Hangouts for iOS has gone live and can be downloaded from the App Store now.
The new Hangouts app will be available Wednesday for Android devices, iOS devices, and on the search company's Chrome browser. It integrates Google Talk, Google + Messenger, and Google's original Hangout video chat service.
The app presents users with a list of recent conversations, and these conversations are persistent, with new information accessible across devices. Users can add and remove participants from conversations and see who exactly has seen what within a particular conversation.
Unifying its diverse communications offerings is part of an ongoing trend for Google, which has been criticized for a lack of focus leading to occasionally lackluster services. Pulling together most of its chat and communication services will bring the search giant into stiffer competition with not only Facebook, but also popular apps like WhatsApp.
The cross-platform Hangouts app will also compete with Apple's FaceTime video chatting service, as well as its iMessage service. While iMessage is restricted to Apple devices such as iPads, iPhones, and Macs, Apple originally intended for FaceTime to be an open standard. The Cupertino company never went through with those plans, though, and FaceTime remains and Apple device exclusive.