akmac - 10:23 pm on Jun 29, 2009 (gmt 0)

If the color of the subject and the background is indeed identical, then I'm afraid some manual tracing will be necessary. If there is a difference, you can tune the magic wand or (photoshop) magnetic lasso tool to make it a bit easier.

Using the magnet lasso tool to trace your subject, then inverting the selection might save you a bit of time.

If you can give a more detailed description of the image(s) you're working with, someone here may be able to give you a better answer.