Also relevant in this discussion: my idea to do this (have GuiHints in some standard location) for both the Pyra and the Pandora, to make it easier for Pandora/Pyra devs to automagically show the correct GuiHint images.
http://boards.openpandora.org/topic/15778-pandorapyra-applications-usrsharepandyra/
(This technique could even be used to lazy-port Pandora/Pyra specific stuff to the PC, by making a PC GuiHints package that has images that look like "Home" for ( A ), "Left Ctrl" for SELECT, etc.)