The USB modem I use is about 1.50 inches wide. There are two USB ports on my MacBook, both right next to one another. When the AirCard is plugged in, I can't plug in anything else. Usually I solve this issue by using a USB extender cable. There are many times that isn't convenient, however. For example, at yesterday's Palm press conference, I plugged the AirCard directly into my computer. Using the extender would have been awkward and left the modem dangling by my leg, where it could be kicked or accidentally caught on something. Palm gave everyone a press kit on a thumb drive. I had to disconnect from the Internet, pull the AirCard out, and then snag the press kit from the thumb drive before re-inserting the AirCard and reconnecting. Quite a pain in the tuckus.
While the USB727 would not have solved that exact problem, it does solve many others for me. I use microSD cards extensively when I'm testing phones. Typically I put some sort of adapter to use when I have to plug the microSD card into my computer. The adapters don't fit when I am using the AirCard. Now I won't have to worry about this. The USB727 supports memory cards up to 4 Gbytes in size.
It may seem like a small time saver to some, but for me, it's one less headache to worry about.