These are all based on popularity and online activity which are terrible indicators for a lot of application domains.
They give you a rough head count yet you have absolutely no idea what percentage of them are actually good programmers you'd want to hire.
Usually the more popular something is, the more you need to weed out bad candidates as well; its kind of killing the popularity argument.
If you pick a technology based on its popularity or visible activity you're only making it much easier for your competitors to crush you really.
I can only refer to pg's Beating the Averages at this point: http://www.paulgraham.com/avg.html