(Note that this is still being worked on, and this is basically a heavy adaption of zoogie's "A Pretty Brief History of the 3ds Hacking/Homebrew Scene" from the "3DS hacking scene history" section on GBAtemp)
2011
March
March marks an important date, the release of the Nintendo 3DS in the west, and the creation of 3dbrew.
June
Not sure about info (come back to later)
September
Crown3DS teases a promising video of a flashcard, but instead we got an Engrish website promising the community that they are progressing.
2012
come back later
2013
2013 is a pretty important year for the 3DS, as this is the year Gateway-3DS released