I was boiling soapy water (to help clean it) in my Martha Stewart stock pot, and I forgot about it. It seems pretty burnt. Can it be cleaned and salvaged, or is it headed for trash? Thanks for your input.
Since the enamel on the outside is OK, it sounds like you didn't get it hot enough to damage the pan itself. So, its probably salvageable.
Check the manual for what they say you can clean it with. For example, if you can use steel wool, soak in soapy water overnight, then apply a lot of elbow grease, that will probably remove a lot of it. Even if you can't use steel wool on it, after a soak one of the non-scratch sponges will probably still help.
Google informs me there are specialty cleaners intended to remove carbon deposits from porcelain/vitreous enamel. You could give one a try if the long soak + elbow grease doesn't work. Make sure to thoroughly remove the cleaner after use, as of course you don't want to be eating it.
The pot may be permanently darkened. That shouldn't affect cooking performance.
Boiling a vinegar-water solution has worked exceptionally well for me in the past - the enamel may be somewhat darkened or discolored even after cleaning, but that's a mark of pride on my pots - it's a sign they're used and often. Everyone in the cupboard pulls their weight. :)