I was talking with the founder of a Startup earlier this year who was looking to have his beta application out quickly. Based on his product, I suggested setting mobile as a number one priority; unfortunately, his response was that only about 30% of cell phone users have smart phones.

• People Who Spend money
  
  One reason to target mobile is that they’ve already demonstrated a willingness to spend money. They are already in a store where most things cost $1 or come with ads. You know that the other 70% DON’T consider technology a need or expose themselves to it – and willingly miss out on other mobile apps – you don’t want to target these people.
• Design is Simple
  A mobile app doesn’t require extensive design to work and be useful while a standalone website does. A mobile app is almost best with the basic iWebKit style interface. If your product has nothing to do with design, this is a great way to worry about functionality first.
• Tools are available
  WordPress has a mobile plugin. Iwebkit is easy. There are a few easy to use tools Appcelerator.