Hell yeah that was some good fun.
Also for anyone playing this on the PC like I am, if you look at the launch menu it says "data files." So that pretty much confirms that there will be something to allow mods or for creation of mods, otherwise Bethesda wouldn't need to put it there.
There are several mods out right now, but none that are created with a construction set. -
http://www.fallout3nexus.com/I'm using MTUI which makes the UI better for us PC users.
I'm actually wondering if they'll release a CS. They may fear that people will create childkilling and nudity mods, and maybe they also want to earn money on their own content instead. My guess is that the data files area is for content that can be bought later. :/ I'm really hoping for a CS though.