The new service has been released in the US, and is available to users who visit the www.google.com/talk page using their Apple device. Users must sign into their Google account, and that’s it – the service runs within the browser.
The Google team explains there are a few differences between the way Google Talk works on an iPhone and a Mac, principally due to the iPhone’s lack of support for background processes: "In order to receive instant messages with Google Talk on your iPhone, the application needs to be open in your Safari browser. When you navigate away to another browser window or application, your status will be changed to "unavailable" and your Google Talk session will be restarted when you return."
Otherwise, its pretty much the same, users can select from a quicklist of the people you contact most, search your contacts, and manage multiple conversations.