Throughout 2005, rumours were constantly floating around about Google's entry into the instant messaging market. In August of the same year, the domain talk.google.com was discovered by inquisitive Internet users and found to be hosting a Jabber server, live and ready for use. Jabber is an open protocol based on XML, designed to be interoperable and extensible. The next day Google announced their instant messenger “Google Talk”, and offered up their custom client for download.
Features
Google Talk is essentially a standard Jabber service, providing access to anybody with a Gmail account (which is practically everybody on the 'net these days, despite the previously exclusive invite-only registration system). You can access it via any Jabber client, although these don't integrate with the extra services Google are offering – namely Gmail notification and free Internet voice calls, the service's main selling point. Conversations are not encrypted, and server-to-server communication facilities are unavailable, meaning that users can't talk to people on other Jabber servers. Furthermore, gateways to popular IM services such as MSN Messenger and AIM are not provided, and as such users of these services are forced to run multiple IM clients (unless they access these services through a multiple service IM client such as Trillian, GAIM or Miranda IM).
Response to the service has generally been critical – people are underwhelmed by this new service in comparison to Google's impressive new technologies such as Google Earth and Gmail. However, due to the power of Google branding, the service is gaining popularity, and users remain hopeful that the service and client will develop and expand.
Client
In true Google style, the client is minimal and functional. It offers a simple white interface with the trademark Google logo and coloured text hovering above the contact list, with a familiar search bar allowing you to search your contacts (should you be popular enough not to be able to find somebody in your long list of friends!). Unfortunately the search bar seems to be a token effort rather than a useful feature – unlike Gmail's extensive archiving, Google Talk only retains a few history items, and it isn't possible to search these. Integration with Gmail is strong however – e-mail alerts pop up as soon as you receive new mail, and a link to your inbox is provided within the client.
The voice messaging functionality is the client's strongest asset. Even on a dial-up connection, conversations are clear and don't suffer from drop outs or disconnections. Certainly the service outdoes its competitors here, and with rumours of deals with other VoIP services which may provide land-line calls, Google is likely to beat all competitors like the all-conquering behemoth it's gradually becoming.
Sources: http://en.wikipedia.org/wiki/Google_Talk, http://www.google.com/talk/