Skype have finally released a beta of their native Symbian app. A few wrinkles as you'd expect with a first beta, but for the most part it's working well on my N86. It supports 3G and WiFi, on-line numbers, text chat...pretty much the full feature set in fact.

Details at http://share.skype.com/sites/garage/2009/12/skype_for_symbian_beta_release.html