[whpalmer4]

All you need to do to share your OmniFocus database between your desktop/laptop, your iPhone, and your husband's iPhone is to set up your husband's iPhone with OmniFocus/MobileMe the same way you did yours. No additional license required.

You should make a practice of occasionally getting all three devices in sync simultaneously. This will help keep your database compact, which will make the sync process for the iPhones run more smoothly.