Is there a way to unwrap an imported object with existing UV seams in Blender 2.5?
In 2.49 there was the “seams from islands” script.
Bump. :eyebrowlift:
bump 
I was looking for this functionality just yesterday as well. It looks like “seams from islands” is missing. My recommendation is to import your model into 2.49 and use that tool there and then bring it into 2.5. Bit of a hassle but not much since Blender is pretty quick.
Found it!
It’s not included in 2.57 stable for some reason.
I recently fixed this so that it works in r37360.
http://projects.blender.org/tracker/download.php/153/468/22929/16755/mesh_seam_from_uv_isles.py
Enjoy!