FBI wiretaps played in court for jurors contain frequent references to "brothers," which prosecutors say means mujahedeen fighters looking for a battle. Defense lawyers contend the term is a common expression among male Muslims.If the AP article has correctly represented the prosecution argument, they must be either absolutely desperate or thoroughly unqualified. As the defense correctly states, "brother" is fairly commonly used between male Muslims, in accordance with a hadith saying that "A Muslim is the brother of a Muslim"; it carries absolutely no implication of being a fighter. Google will turn up numerous examples; for an illustrative sample, consider this slightly frivolous MPAC forum discussion about finding motivational speakers, where other Muslims are called by the terms "brs", "bros", "akhee" (Arabic for "my brother"), and "Brother".
However, in fairness, other reports indicate that the prosecution claims that the defendants used some kind of system of codewords: they claim innocuous words like "picnics", "football", and "marriage" were used with much more sinister intended meanings. If their claim is that "brother" meant "fighter looking for battle" in this alleged code, as opposed to in normal usage, then that might not be completely absurd; I haven't found any transcripts, so I can't attempt to evaluate the plausibility of such a claim.
The usual arguments about the correct translation of "jihad" and "Allah" apparently came up as well - I don't think I'll bother adding to the thousands of web pages discussing that issue.