I recently got around to create a very simple but helpful script to reduce the selection in (face-) edit mode to the ones selected in the UV editor.
http://blenderartists.org/forum/showthread.php?p=897825#post897825
Is there a special procedure how to get something like this into the next blender release?
I’m pretty sure the name of the menu entry and its place may need to be changed to be more clear.
Werner
Just added a second script here:
http://blenderartists.org/forum/showthread.php?p=898587#post898587
And there also is a small problem that’s bothering me with that one:
Does anybody know what group I need to use to get the script into the “Select” menu in the UV/Image editor?
Werner
Select has no slot for python scripts
This feature could probably be added in C, have you tried Shift+H in the UV window with all selected in the 3d view? - its a bit obscure but similar.
Nevermind then. It’s pretty strange though because in the face edit window there are slots available. Was the uv/image editor overlooked when this was added to Blender?
Code in C: Well if s/b wants to do that don’t let me hinder them. I know it’s probably trivial, but I’m sure not going to set up the whole Blender development stuff just to add these 2 mini functions in C 
[Shift][H]: Yes that’s a bit obscure but works quite good … not exactly as expected (the whole island is kept) but still.
On a related note: I could not get [Alt][H] to work. It did nothing after pressing [Shift][H]. I had to reselect the faces in face edit mode. The “Hide” is pretty confusing if one can’t make them visible again :-/
Werner