Rapper states "Planking" Connected to the Slave Trade?

People are upset at the newest internet craze, planking.

Rapper/actor Xzibit explains his thoughts and frustrations with the online pheonomenon.

Xzibit went to his twitter page and tweeted: 

“Planking is the dumbest s**t ever. Planking was a way to transport slaves on ships during the slave trade, it’s not funny. Educate yourselves.
“Don’t get it twisted. I care less where your dumb a**es lay face down and take pictures of the s**t, I’m just telling you where it came from.”

Camilo Smith at TheGrio.com argues that while the connection is not entirely clear, there is evidence of a relationship between planking and the transportation of slaves.

Smith mentions the book, Upon these Shores: Themes in the African-American Experience, 1600 to the Present, which lays out this graphic description:

Some ships had tiny bunks, really nothing more than shelves, on which slaves could recline; in others, the slaves lay side by side on the planking, rolling with the ship, bodies virtually touching, for weeks on end.

What do you think? Is Planking tied to Slavery?