1. Non-verbal IQ has risen more rapidly than has verbal IQ.
2. Performance gains are smallest on the most culturally specific tests, and largest on the most abstract tests.
3. Performance gains, as they occur over time, are roughly constant for all age groups.
4. Problem-solving abilities have seen the biggest performance gains.
5. Gains on the "Ravens" test started occurring before the TV era, much less the computer game era.
#3 is perhaps the biggest surprise to me, as it contradicts most of the obvious explanations for the Flynn effect.
Those results are summed up in the very interesting "The Flynn effect and its relevance to Neuropsychology," by Merrill Hiscock, Journal of Clinical and Experimental Neuropsychology, 2007. Here is Andrew Gelman’s post on that paper.
Hiscock puts it well: "..the Flynn effect constitutes a compelling example of large between-group IQ differences [across generations] that are completely environmental."