I first got wind that age as a marketing segmentation parameter was becoming much less relevant about 3 years ago when I paid a sales call to Castro Model ( a big Israeli fashion house with a chain of retail stores)  to try and sell them a data loss prevention solution from Fidelis Security Systems.  The sales pitch had something to do with protecting fashion designs and was based on common knowledge that there is a lot of design theft in the fashion industry.
I reported back to a female colleague at the office and I commented that the dresses I saw in the showroom seemed to be cut for young girls and would probably not fit her (she is nice looking, in great shape and 40 something…).  Very Bad Idea.
Mary told me – “never tell a woman that a dress is too small for her”.

Fast forward to a project we are doing for a private, professional network for medical representatives and doctors. Our prejudice was that the young doctors are into social media and the older doctors would not use a professional network.  How wrong we were.   It turns out that the the age is not a factor – but the medical specialty of the doctor determines affinity to social media – a 70 year old cardiologist is more high-tech and wired than a 25 year old pediatrician.
So it appears that age is no longer a deciding factor in marketing – and this is for a number of reasons I think:

1. People are in much better shape for their age than 25 years ago and lot more aware of physical fitness
2. The intensity of personal mobile technology like the iPhone and social media like Facebook are crashing the age barrier – my Dad is 87 and he is on Facebook – of course he is a PhD in system science so he is a geek of sorts.
3. Geeks are geeks no matter what age – boomers or pre-schoolers.
4. Second careers – many people who are going into a second career are learning new things and discovering that social media is a great way of marketing themselves.