Old Google Analytics Interface only allowed linking single Adwords account to single Google Analytics account but the New Google Analytics Interface now supports linking multiple Google Adwords accounts to single Google Analytics account.
I have multiple Adwords account for my sites and the old interface created lot more challenges to tracking Adwords ROI for each of the website inside Google Analytics. New Google Analytics account settings area makes it easy to use auto-tagging with multiple Adwords accounts and import your Adwords data into each of your Google Analytics Site Profile.
Instructions on how to link multiple Adwords account can be found on the official Google Analytics Blog here.
I am sure lot of people have been waiting for this feature.