Spam on your cell phone?

We've got the Do Not Call list, and we already have some regulations for email spam. Now a couple of senators are trying to get text messages covered under similar anti-spam legislation. I didn't even know text message spam was a problem. All I've ever gotten are text messages from my service provider trying to get me to sign up for stuff, but I never considered those spam because texts from my service provider are complimentary and also don't count towards my maximum number of storable texts. What about you all - any experience with text message spam? Opinions on this legislation?