A friend of mine got into Sloan directly out of college, but she had been working since her early teens. She had done internships, run her own business, etc. So actually she may have had more work experience than some of her peers given all that she did.
At any rate, she definitely got a few eye rolls about her age and some teasing, but she said she never felt like any of her classmates used age as a reason to make her feel less qualified. If anything they were more impressed.
Me, I'm on the flip side. I'm a couple years older than the average MBA student. And from my visits and some activities, I sometimes feel the age difference, but I think in the end, age, is not really an issue with anyone. Everyone got into business school and is there for a reason. People respect each other and know they need to lean and support each other in their experiences.