I've been getting spammed by this company. I never agreed to get this stuff. THe keep sending me Zoosk ads in the middle of the night over and over again. It also seems that these Airpush guys have made it impossible to opt out of their spam service.
The only option I have found is to download and install this app: https://market.android.com/details?id=com.airpush.optout
which tells you which apps are using the Airpush spam service.
I have no idea what makes them think that this is valuable marketing practice.

The Airpush Detector app and checking my recently run apps helped me solve this. The help came from posted answers on http://www.google.com/support/forum/p/Android+Market/thread?tid=52085e86b6970bad&hl=en
Airpush Detector did indeed detect the spamming app, but I didn't fully trust it because that app was installed months ago and the spamming started yesterday. Holding the home button on my phone pulls up a list of the last 8 run apps. The spamming app was indeed on that list and I hadn't used that app in months. I guess I'll uninstall it. :)
You can get the detector here: https://market.android.com/details?id=com.airpush.optout

Airpush is a telemarketing spam company. You can tell their spam from the red dot but they will likely change this as people become more aware of thier spam. Their spam enables advertisers to push ads to your phone which you have no control over. At first, you won't know what hit you. If you're phone is infected by their spam/malware do the following:

1. You'll see the add in your notification bar.
2. After you press the ad icon (I'm familiar with a red dot inside of a star), carefully watch your screen. You'll briefly see the name of the app that the ad is associated with.
3. Delete the app in order to stop the spam.
4. Download the Airpush op-out app. since I'm sure that this will become more prevalent.

You can also download the detector as others have mentioned, but the correct

detector is here: https://market.android.com/details?id=com.brosmike.airpushdetector

guys just go to airpush.com/optout and you can permanently opt-out of airpush ads.

I've been trying to opt out of this crap for a long time. I did what bason said and that does not work. No way am I going to download a spam app to prevent spam from the same company - that is INSANE!!!!

This detecotr thing that outsmart suggests seems the better option. https://market.android.com/details?id=com.brosmike.airpushdetector

The Opt-out worked just fine for me.
And Airpush messages are not SMS.

Thanks oman for figuring this out who is behind this text message spam. I downloaded the detector and removed the offending application. I get charged for each message so this was costing me a lot of money

HOW CAN I FIND THESE GUYS? I WANT TO RIP OFF THEIR HEADS AND SH1T DOWN THERE THOATS!!!! ANYONE KNOW WHERE THIS ASHER GUY LIVES?

found more info on these guys. Looks like Google is starting to ban this crap.
http://www.reddit.com/r/Android/comments/kbxyl/getting_banned_from_android_market_as_a_developer/