Two things in the Worthen article are worth underscoring:
1- It took Dell a year (I'd say more) to engage with key bloggers
2- Dell has a team of staffers dedicated to tracking online buzz and responding where appropriate
In other words, blogger engagement pay off greatly, just like any other relationship, when you invest the time and energy into it. It's not about using the blogger's space as a sales vehicle. It's about making a valuable contribution to a conversation. It takes time (and in this case budget) to earn street creds...