if you just look at age demographics of facebook users:

http://www.istrategylabs.com/2009/01/2009-facebook-demograph...

40% of facebook users are 18--24.

now compare to people with iphones in 2009 (different to people who queued, admittedly, got stats on this? but still earlyish adopters since 2009 data)

http://gorumors.com/crunchies/age-demographics-of-iphone-use...

whilst for the iphone, very few are in the 18--24 range: just 13%. most people are 35-54.

it seems from this 2009 users of the iphone tend to be older than users of facebook. perhaps because the iphone is an expensive device.