I'm no fan of sleeping in late, I prefer to say that I merely wake up when my body tells me it's time to wake up. With few exceptions, I no longer use an alarm clock and just get up when I wake.
After doing this for about the last 4 years, my "internal" clock has been quite good about waking me when needed. I have little problem going to bed at 3AM and waking up at 6AM when I know I have a commitment (e.g. hockey practice), and on days which I don't, I'm quite good about sleeping in.
Whatever works for my body works for me. One thing I have noticed; however, is that I do have a much more difficult time forcing myself to stay up later, so I do tend to go to bed when I'm tired (typically 2am). Works for me, as I'm more likley to be tapping out bad code which will have to be fixed when I'm tired.