In a previous posting I talked about some questions to ask yourself about your customers use of your SaaS application on mobile devices as a way to help understand how mobile fits into your SaaS business.
It is clear that extending your application with mobile devices is a trend not only in SMB applications but also in Enterprise applications. At this point all of the major SaaS CRM providers have mobile devices as part of their solution. Many vertical industry solutions also have mobile as a key part of their solution particularly when it involves mobile workers.