Can I use one Google Analytics script to roll up multiple sites?

I have dozens of unique domains and want to track each one separately and in aggregate. I've added a unique Analytics tag to each site and the data is coming in nicely.

I'm a little lost on this direction because it doesn't answer if I can do both and I'm not sure why I need to change my links
http://www.google.com/support/analytics/bin/answer.py?answer=45481

Can I also use one tag and put that on every site to roll the data together? What does step 2 in those directions do (is it required)?

Thanks

 

I would have thought that you could just set up another profile in Analytics which you post in addition to the site specific code to get the aggregate data.

Each page will therefore have two calls to analytics, one with the sites individual analytics, and another with the aggregate account.

Obviously this won't be useful for specific page hits (a single page with a common name such as "index.htm" will be counted from all sites) but should be useful for comparing all keywords and traffic.

You might try http://103bees.com/ (keyword / long tail tracking) which will give a count of traffic over all your sites you've got their code on and breakdown for search engine or referral.