Is there data available on physical goods and services traded in BTC? There seems to be plenty of data on the BTC financial market, exchange rates and the like, as well as on the technical aspects (network hash rate, difficulty etc).

I guess I'm not the only one interested in what amount of BTC is spent on actual goods and services, but all I can find is the occasional number by some specific trading platform, for some specific timeframe, nothing more systematic.
There is no way to know this with a 100% accuracy. Because when you look from outside, a trader moving Bitcoins between exchanges is no different from someone paying for a services/goods with Bitcoins. Both are Bitcoin transactions. The same goes for people moving money internationally, sending their parents Bitcoins, a company paying it's employees etc. You really can't separate these from purchases of actual goods and services. Because like I said, they're all transactions.

However, if you want to measure speculative interest in Bitcoin vs. interest in Bitcoin as a currency(i.e for practical things) then you can look at this graph:

http://blockchain.info/charts/tx-trade-ratio

And the discussion about it:

http://codinginmysleep.com/measuring-bitcoin-speculation/

Both the discussion and the data is quite far from conclusive though.