No, not yet. Earlier today Apple's activation servers were down, and people got around it by disconnecting from the Internet while updating the firmware; apparently this bypasses the Internet part of the activation at least, c.f.,
(This workaround was verified by multiple people on Twitter and on HN, see other posts in this thread.) So it sounds like there is a portion of the activation that happens over the Internet, but I don't know whether there's also a carrier wireless network activation.
I just upgraded to 3.0 from my hotel room in Osaka and it worked fine. I put the phone into airplane mode before upgrading, but after the firmware update finished, it was out of airplane mode and communicating with the Softbank mobile network again, so I don't think it made any difference.
http://twitter.com/JeremyCurry/statuses/2211487905
(This workaround was verified by multiple people on Twitter and on HN, see other posts in this thread.) So it sounds like there is a portion of the activation that happens over the Internet, but I don't know whether there's also a carrier wireless network activation.