You could probably just extend the graphicImage renderer to check for the IE browser header and render the code accordingly.
Incidentally, what is the issue with IE displaying PNG's, and what is the fix?
The issue unfortunately has been reported since 1997 and never been fixed thanks to Microsofts policy of not doing anything on the IE since the downfall of Netscape.
The issue itself is, that the IE can render PNGs but has problems with transparency, the funny thing is however that the rendering engine can render the transparencies, simply the IE does not. Since day one of reporting this issue, lots of javascript based bug fixes have been floating the web.
I just ran into this issue again today with a transparent PNG which I tested against the latest patchlevel version of the IE...
I have come to the point that I probably will implement in my sparetime a png image renderer extension to myfaces as you suggested (sparetime means probably in about two weeks ) which I will donate to myfaces.
