We're currently using Twitters open sourced emoji set which you can check out here.
We're also attempting to support the standard set of emoji codes as well. You can see a great cheat sheet here. Note that we don't support all the emoji's listed on this cheat sheet currently. Specifically some of the more esoteric ones like trollface, rage, etc which are part of the official emoji standard
Be sure to thank @Lroot for putting this together!
So... What can I do to not see these? Seriously, there should be a way to view it as plain text. At the very least prevent it from doing this to the p in lain text'.
Emoji require : [insert something here] : codes, so it would not be useful to disable those. However, it would be useful to disable auto-conversion of text emoticons to Emoji.