Facebook and now GTalk (via a Google Labs option) support displaying a phone icon (well, for gtalk it's an android robot icon) if a contact is connected via a mobile device and not a PC.

This has already been implemented as a plugin for pidgin:
http://code.google.com/p/pidgin-jabber-device-client/

But I like Miranda much more than Pidgin so I'd be really happy for this feature, or happier if someone could direct me to a plugin that already implements it - as I couldn't find one :)