In this article in AdAge (Google cache version here), Robert Rosenthal, former president of TBWA/Chiat/Day Latin America, is highly skeptical of what "online advertising [is] actually delivering...." He notes that there is no proper Internet branding to speak of, "[c]an you think of even one "Just do it"...that came from advertising on the web?"
I think this makes the error of thinking about new media by the standards of the old media. It's the view that expects brands to be announcing what they are about the whole time, instead of, well, just doing it. Simply put, it's the expectation of messages where services are more appropriate (and appreciated).
So, there may not be a "Just do it" but there is a Nike+.
As the NYT says, "Behind the shift is a fundamental change in Nike’s view of the role of advertising. No longer are ads primarily meant to grab a person’s attention while they’re trying to do something else — like reading an article. Nike executives say that much of the company’s future advertising spending will take the form of services for consumers, like workout advice, online communities and local sports competitions.
"“We want to find a way to enhance the experience and services, rather than looking for a way to interrupt people from getting to where they want to go,” said Stefan Olander, global director for brand connections at Nike. “How can we provide a service that the consumer goes, ‘Wow, you really made this easier for me’?”"
TV may be the major place for yaddering on about brands and what they stand for but digital offers other ways of making businesses grow - and growth is what 'advertising' has to be aiming to engender.