For people who like a particular look of out of their images, a particular camera's colour and tonal rendition, or would like to replicate a particular film look, Adobe has now unveiled a new program that allows you to easily create custom camera profiles that may be applied to your RAW captures...

Read about it here

This release, in parallel to their release of Lightroom 2.0 and ACR 4.5, also comes as Adobe is releasing updated camera profiles which Adobe says improves colour rendition. As well, you can also try to replicate the particular jpg output of a camera with what Adobe calls Camera Matching profiles, which try to replicate each particular camera's jpg output from the RAW file. And if you like a particular camera's jpg colour rendition, you can use it for another of your camera, like say apply a Canon 300D profile onto a 1DSmk3 image if it so pleases you (why anyone would do this particular combination is a different story and YMMV )

read more about all these here

and here's an article that discusses the software and profiles, and the uses and implications