The workspace at this job is divided with small cubicles just high enough that you don't see the person next to you when you're both sitting.
Recently the worker next to me has been engaging in a lot of long non-work related conversations, either through the phone (in english or in spanish) or in person, with the second person standing up.
Of course small talk is part of the work place, but these talks tend to drag on and on. I getting stressed easily and I simply can't concentrate when there's a conversation happening right next to me. Just this morning the guy spent more than an hour (I timed it) talking to a coworker about his wife. The coworker was standing less than 2 feet away and was leaning on my cubicle panel. I simply couldn't get any work done and had to "go to the restroom" a few times just to vent a bit.
Now I don't care whether or not they're actually working and I'm not there to snitch on them: I believe that if you get work done, so be it. But when they're preventing me from getting my work done, there's a problem. I also don't want to be the guy to tell them to get back to work and I fear that talking about it to my boss (who isn't their boss) would only complicate things. All in all, I may have to work with them later on and I want to keep good relations with my coworkers.
So what can be done about coworkers having long conversations right next to my desk?
EDIT: I have seen this question and, while there is pertinent information there, I feel that this question is different since my situation involves conversations that could be held elsewhere while the this other situation (loud coworker) involves a person being distracting while working.