Android and sim-lock I'd like to know if android phones are sim-locked. Given that they are open-source and have community images it should be 'tricky' to sim-lock one but I prefere to ask.

Also - do I need to unlock if I use dual-sim adapter with one legal card in it?
This differs from carrier to carrier. Some will be sim-locked, some aren't. You'll have to ask your carrier. It has nothing to do with the OS.