I make it a habit to blow out my 360 and PS3 at least once a month. I also keep both of them low to the ground on my component shelf since cooler air sits lower than warm air.
These "current/next" gen consoles run very hot, and if you live in a home with pets or just tend to have a lot of dust build up due to the region you live in or smoking or whatever, being proactive can make the difference between a healthy console and a dead one.