I can't speak from personal experience, more 3rd party experience.
Age doesn't seem matter if you have the right skill set and experience.
A degree alone is going to be less attractive than someone who has actual experience and a degree.
I wouldn't think age would be an issue if you know the technology the company is using and have proof of some projects have you worked on, like a portfolio.
Now if its a early 20's vs an early 30's giving me applications that have the exact same degree and skillset personally I would pick the person that has a family and would be more likely to stay with the company (Generally the older person). (Please note I only do IT hiring not programming hiring so take it with a grain of salt)
Edit: Also don't let someone talk you out of your dream you will get out of it exactly what you put into it.
Depends on the firm really. If its a dev house that does death marches, they favour the young, niave and exploitable.
Let's just say, at my age now, with some of the places I worked in the past, no way in hell I would work under those conditions. Family has taken priority over career, and once you have that perspective, working a 70hour week because some idiot at marketing over promised for E3, or frankly because most managers have the management ability of small furry rodents; well, its just not too palatable. On top of that, people hire people like themselves. So if you have a group of 20-somethings making a game and they are brought in to make an assessment of potentials candidates, they will naturally be drawn to the candidate most like themselves.
Hiring people know this too, so yes in some environments youth and overenthusiasm (aka, exploitablility ) will certainly be favored. This is certainly true for entry level positions... once you've got a great deal of experience, the game changes quit a bit.
As someone who has left the industry completely, I will say in *GENERAL* in IT, ageism exists, especially at the entry level.
As you get in to more experienced positions though, the hiring process changes massively and your resume does more talking. Let's just say, if Michael Abrash interviewed at your company, the process he goes through isn't going to be the same as an entry level Joe. But then, he is probably also coming in to be your boss... ( well except of course for the fact he works for Valve, who practice quasi-organized anarchy ).