The developers behind the Ubuntu Linux distribution aim to significantly improve boot performance. Their ambitious goal for 2010 is to reduce total boot time to 10 seconds. More here
In a presentation at the Ubuntu Developer Summit in Barcelona, developer Scott James Remnant noted that boot time decreased from 65 seconds in version 8.10 to only 25 seconds in 9.04. This is already a substantial improvement, but he believes that there is still room for more aggressive optimization.