I there aren't already there like won't be any.
I guess fewer people see the need to do it now with 1680x1050 option. There might be some companies who do it. I know there used to be companies who replaced the glass or the entire panel to get you a matte screen, why shouldn't they switch panels. The stuff on the old G4 and stuff was usually only DIY people because they weren't that scared to trash such old hardware.
16:10 panels might be not to easy to come by today as almost everything is 16:9.