Looks like the crackdown has begun on tethering apps and the 'free ride' is over. Droid Life are reporting that Verizon are now actively blocking wireless tethering apps on the market. They join AT&T and T-Mobile who have already taken the same measures.
I can confirm that for us Brits it is all good as I just downloaded half a dozen tethering apps through the Android Market (phone AND website). It also seems that for now at least that Sprint haven't blocked the apps. Yet.
I don't understand why some Mobile Networks feel they can not only charge for the data but also how we use it. If I have 1 GB of data a month to burn through does it matter if it is connected to a laptop or not? It shouldn't but apparently it does.
If any readers from a variety of different networks have had tethering apps blocked let us know in the comments below.