A mobile presence is going to become increasingly important. Mike mentions that a lot of startups want to do mobile but simply don't have the resources. That's a very legitimate concern, and it's one you should think about when you are choosing technologies. Frankly, there isn't a very good way to port your Ajax applications over to the mobile world, which is why it is so time consuming. But if you opt to build your application on technologies that work outside the browser, like Rich Internet Applications, it becomes a lot more feasible for your company to leverage mobile technology. A quick tour around the RIA landscape shows a ton of possibilities when porting your applications to mobile devices.
OpenLaszlo recently announced a partnership with Sun to bring their technology to the Java ME platform. That means you'll be able to build your application in OpenLaszlo and deploy it in Flash, DHTML or Mobile. It takes write once, deploy everywhere to a new level.
Adobe's gives you the power of Flash customized for a mobile experience. Flash is already the de-facto standard for multimedia on the web which makes it a very compelling technology for multimedia rich applications. With Flash Lite, you can harness that power and brand it specifically for Flash Lite enabled devices. Adobe is also working on a mobile version of their Flex framework so that you can deploy Flex 2 applications that cater to mobile users.
Finally, Microsoft is planning some very intense integration between Windows Presentation Foundation, their solution for building Rich Internet Applications on the desktop, and Windows Presentation Foundation/Everywhere, which will run on mobile devices and other platforms. They are making it very easy to take WPF code and port it to a WPF/E application so that companies can quickly and easily build a mobile presence.
North America lags severely behind in mobile adoption, and a lot of companies have been able to forego trying to do anything on mobile devices. That is going to change, and it's going to change very quickly. As Mike notes, so many of the Web 2.0 applications are a better fit for mobile devices than they are for desktops. Once people start to demand more, companies are going to be forced to look for solutions that go beyond the browser to cater to those users. If you build your web application from the ground up on these technologies, you get a head start. You can deliver a rich, powerful experience both on the web for the PC and on the mobile web.