Now this is a pretty useful addition to Gmail, Canned Responses.
If you find yourself answering the same question over and over in Gmail, you can just add a canned response and then set a filter to handle who the response gets delivered to automatically.
This is not the same thing as autoresponders, this is more fine tuned to a specific topic or person and not just an email address. Check out the blog post about it at New in Labs: Canned Responses
One thing I realized quickly, there is no obvious way to add a Canned Response?
You have to do it from a Reply window, once you activate it.
Select an email to reply to and there is a new option link to add a canned response.