it's not about Bitcoin. It's about that an exchanger is doing financial transactions. They are receiving money from customers for doing a FINANCIAL service. You need license for a such thing in all the countries. There is NO grey zone.
I don't think these things work the way you think in a lot of places. For example, for withdrawing money in a country where Bitcoin is in the grey area I don't have to pay any kind of tax.
Example: you need a financial license to trade gold even it's virtual gold. Gold is not money...

I need to have a license to trade my FarmVille coins?

yes, you need a license to trade FarmVille coins to cash and cash to FarmVille coins