Frank Shamrock to announce his retirement tonight at Strikeforce: Fedor vs Werdum

Update: It's official.

Gus Johnson on Dan Lebatard's radio show said that Frank Shamrock would be announcing his retirement at tonight's Strikeforce show.

Original "What is Frank Shamrock's 'special announcement' tonight going to be?  Retirement is a safe bet." Post: Last night, Dave Meltzer posted on F4WOnline.com that Showtime has announced a non-fight event as part of tonight's Strikeforce: Fedor vs Wedrum card:

Showtime officials announced tonight that Frank Shamrock, who will be announcing tomorrow night's event from the HP Pavilion in San Jose, would be making a special announcement on the air.

Shamrock, 37, was the first Strikeforce middleweight champion as well as the UFC's middleweight (now light heavyweight champion) from late 1997 until 1999 during a period when he was the organization's biggest star.  He was not fought in the past year, since losing to Nick Diaz on April 11, 2009, in a match he didn't cancel even though he had suffered torn rib cartilage in training.

My guess: Shamrock is offically retiring.  When I interviewed him on Tuesday, there was a telling statement about the shape that he is in now:

"It takes me an hour to get my back straight, and [I'm] standing 90% straight throughout my day."

Hearing him say that inspired the decision not to ask any questions about if he will be fighting again, as it sure sounded like a strong hint that he's not.