Helloes,
I think this would be a very cool way to have accurate statistics about browser usage, not only on Wikipedia.
I was hesitating to work on that simply because it is not interesting as 24/7 statistics of pageviews, though may be interesting to see a day-long snapshots with per-project+per-country split every quarter or so. For that we'd need:
a) good UA header parser (in C...) b) per-country (geoip) aggregator filter c) managed short-term snapshots released every Xth period of time
a) is something I'd be really lazy to write myself b) is on my top-list for other reasons (per-project/per-country counts may be interesting) - so I will eventually implement it (promised it to Stu ;-) c) is a bit... complicated to work on, and _maybe_ could be done manually. of course, it is not much data, so we can leave it running non/stop, with daily aggregation schedule.