A couple of months ago, Google finally announced an official integration between Google AdSense and Google Analytics. The announcement was made in a post, Make a date with data in Google Analytics, on the Inside AdSense Blog.
I received my invitation about a month ago. It took some time for enough data to be collected for the data to be reliably useful.
The ability to see AdSense Revenue, CTR and eCPM for every page is extremely useful. The ability to see AdSense these statistics for each incoming keyword is no less useful.
This data helps me top decide where to spend money. It helps me decide what kind of content to build and which keywords to promote.
Over time, I expect that this data will help me to significantly increase my AdSense revenue.
If you don't have an Analytics account yet, get one now. That's the only way I know of to get in line for an invitation.