The current Skype client for S60 is written in J2ME. J2ME is not full Java implementation. It is a stripped/embedded version (Mobile Edition).

Skype client for Linux requires Qt.

If you read the news about Nokia & Skype partnership it is integrated in the OS, and it will be included in the N97 firmware. Is J2ME by default installed on Nokia N-Series?

Skype is also porting to Android and Mobilin. But these are 'light' versions.

So at least part of the code is cross-platform, and its ported to ARM, and the full Linux version uses Qt. Perhaps a full Linux version ported to ARM is not far-fetched.

In any case, I don't mind that they want to profit on their infrastructure but I do think its nice to be able to pick your own VoIP client. Thats why I suggest SIP and open IM protocols like Jabber.