Recently, the Google Analytics engineering team added the ability to allow you to link your Google Analytics account to your AdWords account:

Just log in to your AdWords account at https://adwords.google.com and click the Analytics tab. Then:

1. Click I already have an Analytics account
2. Enter the email address and password for your Google Analytics account. Note that you must be an Account Administrator on that account to be able to link it to AdWords
3. Click Link Account

That's it! Your two accounts are now linked, and Analytics will start automatically tagging your AdWords links for detailed campaign tracking reports.

Here's the article at the Google Analytics Help Center.