Advertising Age has published this article by Positioning author Al Ries.
In a nutshell - six steps a PR brand launch might take:
- A leak to key reporters and editors of online news
- Slow buildup to allow time for PR to develop momentum
- Recruit distributors and other allies
- Get feedback prior to actual product launch, modify product accordingly
- Modify brand message per media feedback
- Do a soft launch: Facebook was first launched on one campus in 2004, was still being rolled out further in 2007.
Al Ries says:
"In almost every way, the launch of a brand via PR is exactly the opposite of how a brand is currently launched with an advertising program."
You should read the article - short but good.