What, like a TC-80N3?
But then you won't have to spend another $160 on a TC-80N3... (like you would anyway, ebay has chinese ripoffs for $20).
Still, it would be nice, and can be done, there's an inbuilt timer in the Pentax K-5. Main thing is, having one in-camera means you don't have to open a weather-sealed port like on my 7D to plug in my TC-80N3.
If I ever have/want to do some star-trail-shooting that requires me to leave a camera set up overnight while i go in to a tent to sleep, and i'm worried about rain or dew, i'm stealing my mum's K5 (with weathersealed 18-55 kit lens), the 7D will stay at home.
(If only Pentax were big enough to provide real competition to Canon, it's always the little guys that innovate and the big ones that do nothing but get fat profits from doing nothing [/rant])