According to Will Sturgeon over at Silicon.com, spam on mobile devices is becoming a problem. He cites that over 2/3 of mobile users have gotten an unsolicited SMS. However unlike email, SMS has a cost to it--usually a per message fee. It's not nearly as cheap to send out say 1 million text messages as it is a million emails.
That being said, a lot of the spam is directly from the wireles co's who don't have a per-message cost. Spamming users should be against company policies, but for most it is a routine procedure.
We're interested in what spam you've gotten. Commenting is open for this post--please use it (even if you want to say you've never been spammed). Also, if you can make sure to add in what carrier you use and if you've gotten spam from them... It will help out those who are looking to get a new service provider.