The average age of gamers is 37? I find that a bit incredible.
Public perception is certainly different.
Nintendo in particular have done an brilliant job of taking their platforms into older markets. My parent's, in their sixties, both have DS's, share a Wii and play many desktop games (due to my influence, of which I'm very proud).
People in to 30-50 age range have also grown up with the growth of the leisure computing industry, they may well have taken up gaming when the were the correct age (the media expects you to be) to start playing, and never put it down.
Also with the growing size of the 'the old' in relation to 'the young' the 30+ age range is probably (guessing) a bigger and growing market share, bring the average up.
I have a terrible grasp of things like statistics so I'll avoid making any kind of leap of logic here and suggest this means anything, but I just thought it was an interesting coincidence if anything.
The real thing that skews these stats is that "gaming" includes angry birds, it includes facebook games, it includes... etc. etc. Those are the games that skew the stats.
People actually in the industry see past it, when marketing WoW, or Call of Duty, or whatever latest big title, the focus is generally described as 18-30 (or sometimes 18-25), with the assumption that despite not saying it, naturally you also want to attract the under 18 market as well. It's just the media who get fooled by the figures into thinking gaming is for the old, now.
Edit: that's not to say that it isn't going to go up (and has already begun), because obviously as the generations move up, they carry with them acceptance for gaming. But it hasn't yet happened nearly as much, for what we think of as big video games at least, as numbers suggest.
Note: I am 100+ person guild where more people are over 50 than under 20. We raid 2 nights a week and are middle of the road when it comes to progression aka top 10,000 ;o guild world wide. http://www.wowprogress.com/guild/us/malygos/Wasted+Epics
And more to the point: as game billing is generally per-seat or per-month, it's these older players that actually dominate the revenue.