Shall I do business with it?

Dear all,
According to the possibilities, (Im really new on this) I don’t know if is legal attach an arduino to a project and sell it? Can someone to tell me if its possible or where I can read / learn conditions about it? I mean, is very useful in industries help on production process like conveyors, controlling small production lines, or big ones, is just a question of creativity. But, if I have a production process and I want to attach a brain like one of those arduinos… could I make some money with the result?
Regards!

Yes.
You may want to do a custom board tho for more secure connections, account for power sources, signal drivers needed, etc.

but I mean, I can use it, sell it and make profit with it?
lets say I use it to control few motors in a converyor and sell it...?
thanks!

Yes you can do what you want. That is the point about open source stuff.

Official FAQ answer your question in more detail: http://arduino.cc/en/Main/FAQ