So I'm trying to make a kinda complex site, and this guy I know offers me this framework his company is using, saying thats ok if I want to use it. Now, the thing is, what if my site becomes somewhat succesful? I'm not talking about myspace-succesful, just enough to get some ads. But what about his company? could they sue me for using their framework? Dunno, could that be considered an IP as it is?
Short answer: yes. Long answer: depends on what this "framework" actually is and how you are using it. I would still venture a guess that any commercial use would get you in trouble and any non-commercial use could get you in trouble if the company finds out.
If he gives you permission to use it for free then he has no claim to any profits you make. However, he could lie later on and say you stole it, then sue you. It depends on how much you trust this fellow.
A framework would be classified as copyrighted material - so even if your friend wrote it, whilst working for a company the company would still own it. If you're concerned about possible commercial usage I'd avoid it - unless you get specific written approval from whoever wrote it first.
Indeed, reason why I'm going to make him sign a contract. I dont even know the guy, he showed up after a post I made in some freelancer coder forum. Yeah I was thinking the same, specially after a court ruled that a verbal contract cant determinate that the facebook creator stole the idea from a fellow student at harvard. If the sites becomes somewhat sucessful, some lawyer with a lawsuit from a crappy web company is the last thing I need...