Just got a very interesting unsolicited call from an occasional contact who knows some of these players pretty well. Someone one would more than expect to be extremely friendly to their positions as well. And he told me that:
1) The charges against Chalabi passing highly sensitive US intelligence to Iranian intelligence are true.
2) It involves a piece or pieces of signals intelligence. Intelligence involving how the US listens to Iranian communications, who it taps, bugging, etc.
3) The evidence of Chalabi's intelligence breach came to the US government from a European government. The proof was given to the US by a European government/intelligence agency.
The timing of Tony Blair's visit with Bush in Washington April 16, 2004 is looking more and more interesting. Since mid-April seems to be the time that decisively turned the White House against Chalabi. Made it turn on a dime.
UPDATE: Kevin Drum urges caution about the intel on Chalabi, given how flawed the US and UK's pre-war Iraq intel proved to be. Agreed. In addition, let me just clarify, that it was my presumption that the European government that might have been the one which allegedly presented evidence of Chalabi's espionage to the US was Britain. My guess that it might very well have been Britain was based largely on the facts that 1) two people including the source above told me that the evidence the US received about Chalabi's betrayal came not initially from a US domestic intelligence agency but in fact from a trusted European government/intelligence agency, and 2) then my deducing that the timing of the White House decisively cutting off Chalabi came in mid April, around the same time Blair visited Bush to talk matters Iraq. I think it's important to keep in mind - and this has been reiterated by numerous sources - that it was the White House that decided to cut Chalabi off, around mid April.
Thanks to Atrios for the mention.