Interoperable Mobile Messenger?

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After the wonderful interoperability of Yahoo Messenger and Windows Live Messenger, I can finally chat with my friends who use Windows Live right from within my Yahoo Messenger application. But I was wondering if there is a mobile messenger out there that can do the same thing for the mobile phone. I've tried some (the likes of Morange, etc.), but they still require you to have separate accounts for each provider. Does anyone know of a mobile messenger which allows me to see my Windows Live pals right from my Yahoo Messenger account? I don't really fancy to have multiple IM accounts.