If he's really being bullied by most of the team, it's a very difficult situation to deal with.

If he's an extreme geek though, it's possible that he's misreading the situation. Sometimes geeks interpret indifference/lack of interest as hostility.

Best option if possible is to get a new job.

Otherwise, best thing is to escalate things progressively.

Start by talking to the other developers peer-to-peer about concrete matters. "Hi, I really need information X. I was unable to achieve Y because you didn't tell me about Z".

Read How To Win Friends and Influence People and use the techniques there.

Only if that doesn't work, get political. If they're not really hostile at the start, getting political will make them hostile.

Document everything. Save every email. PROVE that your work is suffering due to others as SPECIFICALLY as possible.

CC the boss in on important emails. "Hi I really need to know A or project B will be delayed".

Consider talking to HR about the situation. They might be helpful, or might not.

I helped write a thing called Politics Oriented Software Development on K5 years ago, though it's mostly about dealing with management not peers.

Thanks for the good read, Theophile.

What Obscure Reference said. Interesting.

And agreeing that if the problem is withholding information, an email to the owner of task foo, CC'ed to the boss, explicitly saying "I need foo to proceed with bar because of zork" should be the first step.

That doesn't sound like bullying though, more likely that foo is behind schedule and they're stalling, so there is probably something involved we haven't heard yet.

The immediate problem for which information was being withheld has been dealt with, there is no HR but he went to management. The team is extremely cliquey and have been hostile since day one six months ago. He has never mentioned a problem up til now so things must have gotten very serious. He would like to find a new job but they are scarce. It all started off with such promise but I think he has been fighting miserable circumstances where he is never getting to take the direct way through to a problem and always having to make the awkward journey around as far as actual work is concerned. I am hoping he gets flexible hours and can work some from home until he finds something. All the free beer and games don't make up for super cliquey geeks at work. I'm glad the current crisis is resolved but now I know what a constant pressure he's been under with a sucky work situation and there's really nothing I could do but hope to find him a job.