It is a myth that guys never speak or look at each other in the bathroom. I can't count the number of times another guy has made eye contact or talked to me in there.
I think it depends on age, maturity level, confidence, and familiarity, among other factors (location, norms of that location, etc). How old are the guys you work with? How close are they? Do they use a lot of sexual or "raunchy" humor with each other?
I've found that, amongst strangers, sometimes older gentlemen will attempt a conversation with me. Younger men just make brief eye contact and a nod of recognition. A lot of guys, though, are the stereotypical avoidant type.
This all changes at school and work though. Like Liam, I've also held conversations in the bathroom with my classmates (I'm in college). I let them initiate it, however. I say as little as possible without being rude because I'm uncomfortable with talking in the bathroom (mostly because of things I've read from other trans* people). One guy will piss at the urinal and talk to me while I wash my hands. It's a little odd, but he's also a very confident guy and we've known each other for 2 years now. It's actually fairly normal for the guys in my class to joke or talk to each other in the bathroom. I haven't seen anyone try to peek, but I wouldn't be surprised.