gridmarket, tell certain category pages to display in blocks, or "grid" like the store

on our current site,

http://ronaproject.com/blog/category/videos/

the posts being displayed in the category there are being displayed just like the store display of frame market.

id like to do just this, not necessarily 2 blocks side by side, but the same concept, im thinking id like to make this display in 3 columns across.

thanks!