Inside my indoor garden, my compact fluorescent light fell from the top of the cabinet, and smashed onto the pot. Since its in a generally sealed container, can it be poisonous? and will it ruin my plants?

yes, the gas inside a compact fluorescent lightbulb is mercury vapor.
you are a dumbass for buying a lightbulb that contains gas that is outlawed in any other product, due to poisonous reasons.
the gov't sucks because they are mandating these hazardous lightbulbs
</political rant>

if you have had exposure to the gas, thats bad. check here for symptoms:
http://www.mercury-poisoning-symptom.com/

there is really no treatment. an ER didn't know how to treat my friend who was having migraines, blurred vision, etc. due to a broken compact fluorescent.

proper disposal of the broken lightbulb is to call in a Haz-Mat team- i am not kidding.

best of luck.

(stock up on cheap, regular, non-poisoning lightbulbs while you can!!!)