It is currently taking up the maximum of 2k (roughly).
There is optiboot which has been developed which only takes about 1/4 of that, about 0.5k, and it may replace the standard arduino bootloader soon.
You can download it and stick it on your arduino yourself though if you have an ISP programmer (or a second arduino to act as one).
Mowcius
There are no bugs, limitation etc. using that optiboot?