Well, strictly speaking, the 2nd Circuit in the USA has held that Google’s sale of keywords may be use in commerce.
Rescuecom had sued Google for trademark infringement by selling advertisements (sponsored links) triggered by Rescuecom’s trademark. The District Court had dismissed the claim on the grounds that Google’s conduct was not use in commerce. So now it goes back to the District Court.
Of course, Google’s conduct, if were done in Australia or transacted with a business located in Australia, would be in trade or commerce for the purposes of the Trade Practices Act. In context, however, the nearest analogue under our law is whether or not the conduct might be “use as a trade mark” (in the sense of using the sign in the course of trade) for the purposes of s 120 of the Trade Marks Act.
Professor Goldman considers the ramifications under US law (and the distinguishing of WhenU) here.