The Mark Walsh era at Air America Radio has come to an end...a full three weeks after it began.

The Chicago Tribune is reporting (registration required) Walsh "stepped down" as boss at the liberal-leaning radio network on Monday.

Air America - which officially went live on March 31 - has already been kicked off its stations in Chicago and Los Angeles and grappled with bad press from an alleged check-bouncing controversy. (However, fans in those two cities can still hear Air America programming via the prestigious Internet.)

Rush Limbaugh, whose afternoon, nationally syndicated radio program competes with Air America star Al Franken, said on his show this afternoon that Walsh and Air America parted ways shortly after Walsh made a bombastic, anti-Limbaugh speech before a trade group.

There's more discussion of this story over at the New York Radio Message Board.