I'm going to nitpick that article. Not all of the coverage of Trello at Disrupt came from writing reporters ahead of time. I know because I wrote one that mentioned Trello: http://www.wired.com/2011/09/startups-techcrunch-disrupt/ and Joel did not pre-brief me or Mike.
He namechecks this great older post on PR and conferences and how to launch: http://joelonsoftware.com/items/2011/09/15.html
Worth a re-look for every startup founder
The shortest possible version is: launch is important