When you first load up OS X on the new MBA, it will ask if you want to import from a Time Machine backup.
Or you can set everything up and then use migration assistant to import from a TM backup.
Keep in mind that if you want to import using migration assistant and want to keep the exact same username/Full Name, do NOT create that same user account when setting up Lion. Create a dummy account that will get deleted once you finish importing. If you don't care about keeping the exact username, you can import the content to as a new user.