Thanks to (the other) Ewan for pointing out the existence of Nimbuzz, which hasn't actually formally launched yet. It's yet another VoIP/IM client for phones, but it's distinguished so far by having a native S60 client (kudos) already, by supporting Skype chat (yay for the AAS office) and by having the slickest and smoothest Web 2.0 download, sign-up and install I think I've ever experienced. Mobile VoIP isn't truly there yet though. As with Skype Mobile, a chargable gateway is used, though full VoIP is apparently on the way, as per Fring.