Mike Hawash (of FreeMikeHawash fame), the former Intel employee held in secret for five weeks as a "material witness" before he was charged, has plead guilty and has agreed to testify against his alleged fellow conspirators in a plot to go to Afghanistan in 2001 to help the Taliban, according to this article from CNN.
Considering the conspiracy charge, and the guilty plea, there is more reason to ponder whether the use of the "material witness" mechanism was appropriate, since clearly he is a witness in the proceedings against his coconspirators.
Interesting notes about this case:
The FreeMikeHawash web site has now moved to "support for the family" mode, instead of trying to actually get him freed (I would imagine that the guilty plea has changed that a bit).
Hawash will spend at least 7 years in federal prison based on the plea agreement.
The affidavit filed this spring contains some interesting date coincidences. In particular, although claims are that he started changing after September 11th, he signed a general power of attorney over to his wife on September 9th. My guess is that he was having problems at home, but it is hard to tell from the information available, and if he knew about September 11th ahead of time, it would make more sense.