Terry White answers the question, "How do I open up a JPG file in Camera RAW?" and shows how to take advantage of Adobe Camera RAW's ease of use and non-destructive workflow.
In a 2009 Creative Cow video, AE Quicktips #8: Camera Raw Sequences, Carl Larsen showed a similar way to import a .jpeg or .tiff sequence into After Effects with Camera Raw development settings applied. There's more on using RAW files in After Effects Help; things will work smoother if app versions are in sync.
Update: on the AE-List November 2011, Chris Prosser (software engineering manager for After Effects) said "Alas, RAW is just slow. The engine highly optimizes quality over speed due to its heritage. I often will convert them to a better intermediate format (some kind of 16 bit format)."