The first generation of bloggers (that were 'blogging for money') for the most part, had two choices. Google's Adsense or one of the affiliate networks.
The landscape is changing.
Bloggers are seeking direct advertisers. Analytics are now concise and can be easily e-mailed to a potential advertiser or sponsor.
Many early and current bloggers work 12-15 hours a day writing, marketing and networking (Really!).
They don't want to guess what this month's paycheck is going to look like anymore.
There is also growing monetization of RSS feeds.
With the advent and growth of feed sharing, what was once a secondary income is now significantly larger (and so are the ads).
What's not being seen (yet) are numerous advertisers now in this space, studying relatively inexpensive ways of driving traffic. They don't want to outsource. They want to see first hand where their business is coming from, and, in a soft economy, build their own networks and 'deal direct'.
For many media buyers, large and small, it's become an ongoing assignment.
Adsense and the affiliate networks won't suffer. Websites and blogs will use them for a long time. More will appear every day. There will always be advantages for some to 'outsource'.
More mature publications (websites, blogs, etc. with a significant following) will start to notice the shift to direct buys as advertisers begin to approach them.
Google's recent shift to it's DoubleClick product wasn't a coincidence.
It's part of the evolving convergence of traditional and Internet media.
Edited July 8 PM