Generally when you want to update iOS on your iPad or iPhone, you have to download the update through iTunes and plug in your hardware to your computer through USB. Verizon Wireless does not want you to go through that kind of hassle any more.
According to a source with 9to5Mac, iOS5 will be able to be updated on your iPhone or iPad over the air through a network connection. Apple and Verizon are specifically talking about adding this feature.
One of the biggest challenges with adding this feature is the size of the operating system updates. Some of the updates are over 600MB. That would put a tremendous amount of pressure on phone company data networks.