There are six candidates named in the criminal complaint against Rod Blagojevich. This is my attempt to parse who is who:
Candidate 1: The complaint describes Candidate 1 as an "adviser to the president-elect" and that "media reports indicated" she was interested in the seat. Blagojevich also refers to Candidate 1 as a "her" in the complain transcripts. All in all, this suggests that candidate 1 is Valerie Jarret.
Candidate 2: The complaint says that Candidate 2 was deliberately leaked by Blagojevich to a columnist in the Chicago Sun-Times, and discussed in a column on November 7. On November 7, Sun-Times columnist Michael Sneed weighed the possibility that Illinois AG Lisa Madigan could be appointed to the seat. Blagojevich apparently wanted her name leaked to "send a message" to Obama without Obama knowing it was from Blagojevich himself.
Candidate 3: Only mentioned once, so difficult to speculate.
Candidate 4: This is someone close to Blagojevich, in the complaint transcript Blagojevich refers to Candidate 4 as someone who would give up the Senate seat for him if need be. Blagojevich allegedly said that he could “count on [Senate Candidate 4], if things got hot, to give [the Senate seat] up and let me parachute over there” in case Blagojevich was indicted. Candidate 4 is also identified as "a deputy governor of Illinois." Current Deputy governors include Dean Martinez, Bob Greenlee and Louanner Peters.
Candidate 5: Marc Ambinder has made a convincing case that Candidate 5 is Jesse Jackson Jr. Candidate 5 allegedly offered Blagojevich half a million dollars for Obama's former senate seat, and judging by the complaint, one of Obama's less favored picks. Blagojevich, according to the complaint, said he would pick Candidate 5 if Obama "didnt' give him anything".
Candidate 6: Candidate 6 is described in the complaint as a "wealthy person from Illinois." I have my suspicions about who this is based on previous speculation in Chicago newspapers about possible Senate replacements for Obama, but they're pretty much uneducated guesses so I'll keep silent for now.
All of this is pretty nuts. Blagojevich was already under investigation when he undertook an effort to sell the former senate seat of the president elect, which, as an act of ballsy self-suicide is up there with the end of Scarface. Reading through the indictment though, it looks at first glance like the Obama team had very little to do with Blagojevich's efforts, and in fact frustrated him with their unwillingness to negotiate for the seat. According to the complaint, Obama wasn't offering Blagojevich anything other than "appreciation" for picking his preferred candidate.
UPDATE: Ben Smith points out that another possibility for candidate 5 is House Rep. Art Turner, who was most recently named in Michael Sneed's column as a possible appointment. The complaint suggests that Blagojevich had recently "leaked" information about Candidate 5 to a "Sun-Times columnist" who, as I explain above, was most likely Sneed.
UPDATE 2: Candidate 5 may also be Illinois State Legislator Emil Jones Jr.