I get a lot of different stories about this from BrE speakers, though. Some say they were taught at school that the plural verb is ungrammatical here and you have to use the singular; others (maybe from a different area) tell me that it is the singular that would be ungrammatical; others can do both without a difference in interpretation; some can do both, but they get slightly different interpretations (for example: "The committee is old" is a statement about the age of the committee, while "The committee are old" is a statement about the age of the committee members).
What about you? Do you prefer singular or plural agreement with group nouns, or can you do both? If you can do both, does that lead to a difference in interpretation? If you prefer plural agreement, can you do it with non-human animate groups (like "the flock" or "the herd") or is it really only for human groups? Are there any regional differences?
Please feel free to share any other interesting observations you might have :).