The article by Peter Harvey (posted by Chris) is interesting and like most discussions on vegetarianism and Buddhism, focuses on the Vinaya and rules for monks. It may be true that many lay Theravadins do choose to eat meat and one reason may be that they feel monks are held to a higher standard and as the quote goes, something like, "if it's okay for them it sure must be for me." That may be a common sentiment, but I find that more attention must be given to what I buy, not because as a layman I have a higher standard (of course not), but rather that we have that choice at all. The Threefold rule appears to be mostly about not being choosy and graciously accepting what is offered, not denying the merit making for the lay people.
If everyone were Buddhist there would be no slaughterhouses and no meat available (who would do the killing), so by this fact alone, vegetarianism at least might be seen as an "ideal" or as Harvey puts it, "universally admired."
I understand that vegetarian Buddhists should not judge those who eat meat just as those who eat meat should not judge or condemn vegetarians; I am just noticing that in Suttas that are not just directed at monks and nuns, there are plenty of references to not killing or causing to kill. For some, this may mean trying to reduce the number of animals slaughtered in a way that feels appropriate. For others it is a matter of not directly killing or requesting another to kill.
The list about what breaks the First precept can be seen in a literal way, which is understandable and explained well by Bhikkhu Pesala and Bhante Dhammanando. For others the list may imply that certain actions and words might condone or defend killing. I don't know. Since I am not sure and certainly don't want to speak in praise of killing, when in doubt I figure if I am in error, let me err on the side of life. I'm making no judgments, just my opinion!