I don't know if they work in the Pazzles or KNK, but the Cricut blades will work in the Gazelle, as will Pazzle blades. Cricut and Pazzles mats will work in the Gazelle too!
Have I confused you yet?
Edit: Cricut EXPRESSION mats work. Sorry, should have clarified that. The smaller 6"x12" mats don't work in the Gazelle because they aren't wide enough. That being said though, I buy my mats from Scrap-mart.com with my 40% code, and they are awesome and sturdier than Cricut mats. I just paid $12.50 for 2 Gazelle mats with free shipping. I tape off the edges and spray them once the adhesive starts to wear off. Well, first I wash them off. Then tape them off, then spray, and 10 minutes later I have a like-new mat! I still have my original mat, I just bought an extra pack because I have a big cut job coming up to help a friend with a project and I didn't want to suddenly have a ruined mat and have to wait a week for the new one to get here!