[UPDATE 2: the BHO campaign changed their website, possibly to admit that he was indeed an ACORN trainer.]

Barack Obama has been caught in yet another of his lies. Here's what his "Fight the Smears" website says about his involvement with ACORN (fightthesmears.com/articles/20/acornrumor):

Discredited Republican voter-suppression guru Ken Blackwell is attacking Barack Obama with naked lies about his supposed connection to ACORN.

* Fact: Barack was never an ACORN community organizer.
* Fact: Barack was never an ACORN trainer and never worked for ACORN in any other capacity.
* Fact: ACORN was not part of Project Vote, the successful voter registration drive Barack ran in 1992.

Now, turn to a 2004 article from Social Policy, which was apparently scrubbed from their site [1]. That article was uncovered by this site, which has more:

"Obama took the case, known as ACORN vs. Edgar (the name of the Republican governor at the time) and we won. Obama then went on to run a voter registration project with Project VOTE in 1992 that made it possible for Carol Moseley Braun to win the Senate that year. Project VOTE delivered 50,000 newly registered voters in that campaign (ACORN delivered about 5,000 of them).

Since then, we have invited Obama to our leadership training sessions to run the session on power every year, and, as a result, many of our newly developing leaders got to know him before he ever ran for office. Thus it was natural for many of us to be active volunteers in his first campaign for STate Senate and then his failed bid for U.S. Congress in 1996. By the time he ran for U.S. Senate, we were old friends."

[1] It was previously at socialpolicy.org/index.php?id=838. That page now returns a listing of other articles, but an 10/4/08 cache is here. That page requires a login, but if they've removed the original page it probably wouldn't work even if you signed up.

UPDATE 3: See also ACORN Ohio worked *with* Obama campaign on GOTV; ACORN/Project Vote did GOTV in battleground states

UPDATE 2: There's much more on ACORN and Obama here, here, here, and here.

UPDATE: Here's a McCain campaign video about BHO's involvement with ACORN: