Marketers dream for this type of targeting. Now, instead of an ad that people ignore, you could get a message delivered directly to these people. I, for one, would gladly pay $1 per targeted delivery of message.
If the system works as elegantly as Google Adwords, this will be big. It could go either way though. 1) users revolt against this and it flops, or 2) users actually like the messages from high bidders because it targets them especially well.
Will be exciting to see which way it turns out