I’ll keep this short and sweet. Google is heavily involved in the mobile market (think ‘Droid). They know that mobile apps are fast becoming a mainstay of programmers, who are opting out of the PC rat-race for greener pastures. That said; they also know that more and more people rely on their mobile devices everyday for things they used to use a home computer for – including search.
There is a great deal of money to be made in mobile computing today, and mobile search tomorrow. Plan ahead and get in on a great thing at the ground level. It will not take much.
In reality, you just need a few mobile pages woven into your existing site. You can make things as easy or complex as you like, but I suggest easy – at least for starters.
The quickest and easiest way to get in on this game is to include some content pages in a mobile format (320 by 240 pixels is usually a good place to start but your developer will know for sure).
Be sure to exclude complex, and/or resource hog elements like Flash. And if you have images on any mobile page, include alt tags to save your visitor some frustration (and rank better).
That’s about it. This one is simple. If you can afford to add a few mobile pages to get things going, that would be ideal. The sooner Google indexes them, the better off you will be.