IMpressive
Google's latest beta project has just hit the 'net, with yesterday's announcement of Google Talk, yet another Instant Messenger system.
The interesting thing about this one is that firstly, they're using the free Jabber protocol, rather than creating their own, so any client that supports Jabber can connect to the service. Not only that, but they're actively encouraging people to use third party clients (particularly on currently-unsupported platforms, though Linux and OS X ports are promised), as they express the belief that people should be free to use whatever client they wish. This is different to the other mainstream providers who frequently alter their own protocols in order to foil free software developers attempting to connect to their service.
This is particularly important given that services aren't compatible, resulting in some people running multiple clients to connect to many of their friends' preferred networks. Multi-protocol clients such as Gaim will allow you to connect to many networks without the need for a seperate client for each and since Gaim already supports Jabber, adding a Google Talk account to it is trivial.
Google are aware of this issue too and so are attempting to a situation similar to telephone and email where people should be able to IM anyone, regardless of provider. If they can use their not-insignificant influence to bring this about, things'll be a whole lot simpler.