Check this out. A company called MobiUS released a very cool, and very portable, ultrasound system. The system is primarily comprised of the wand and a smartphone. Because both of these components are so small and portable, the entire system is very mobile and inexpensive to use. Further, because the device stores the data in a phone, it makes sharing the data very easy.
I think it's really interesting to see all the new applications coming out of smartphones. I'd like to see what other innovations we might see from smartphones.