That's why we need to separate the protocol from the UI. There is absolutely no good reason why the different platforms should disallow communication with each other.
I used to use a multiprotocol client, Pidgin, to chat with people on a couple of different platforms. But of course now a lot of chat is on things like Facebook and Google Chat which are supported only by plugins.
But even that is still not enough because I will have to have an account on each of the platforms.
Chat really needs to be like email or SMS; you ought not to need an account with the provider of the person you are sending messages to.
I used to use a multiprotocol client, Pidgin, to chat with people on a couple of different platforms. But of course now a lot of chat is on things like Facebook and Google Chat which are supported only by plugins. But even that is still not enough because I will have to have an account on each of the platforms.
Chat really needs to be like email or SMS; you ought not to need an account with the provider of the person you are sending messages to.