Last summer's kerfuffle over the fan-produced King's Quest sequel The Silver Lining was fortunately resolved without legal bloodshed when Activision (current owner of the Sierra intellectual properties) consented to allow its release, after an outpouring of support from fans including Roberta Williams herself.
UPDATE 02/20/2011: Of course, now we know why Activision was being all protective, as the episodic adventure publisher Telltale Games has announced an upcoming official King's Quest revival.
If Sierra On-Line were still in business, it might have been easier to resolve the whole matter by bringing up Mr. Cool:
One imagines the gaming community rallying to champion a lovingly produced, non-profit fan effort against a company that once kept its balance sheet healthy with a quickie Q*Bert rip-off (not to mention the Donkey Kong-"inspired" Cannonball Blitz.)
But fortunately it all worked out. As John Lennon once sang, instant karma gonna get you.