Apparently there are a lot of IRC networks that Verizon has blocked on their servers directly. So there are only a few IRC networks you can access, the ones that they deem "will give verizon customers the best user experience" as stated on verizons website by one of their droid x users after he called VZ to complain.
Here is the thread, it was the 2nd from the bottom when I last read it (9th from the top).
Edit ---- This is for accessing IRC servers via 3G (wireless isn't using their servers), going wireless may be the only way to access the other servers until enough people complain, or leave Verizon as a company thus making the cost of maintaining the blocks too high.