HART recently announced its participation in the One Bus Away project which in turn provides the first user-side GPS tool the riding public has actual access to. In a nutshell this implemention of the project in Tampa allows riders to, from their home or from on the curb, check the real-time arrival information for the next bus. A previous system by HART allowed riders to better look up fixed schedule information from their smartphones, but this data differs in that it is real-time.
I believe that GPS-assisted transit services are especially potent in a medium-sized city like Tampa for two reasons: One, Tampa operates an excellent, but from a budgetary viewpoint, skeleton system. It's all about buses, streetcar line aside, with 15+ minute head-ways on most routes, which is just adequate to supplement core living needs and some choice rides across the class spectrum.
As I see it, if buses averaged faster head-ways GPS-assisted transit wouldn't represent as valuable a gain because users would already understand that to merely show up at a bus stop would be to board a bus almost instantly. If buses ran too sparsely, however, there wouldn't be a rider base in the first place. So I believe the current situation is optimal for filling in the gap between a bus that is in fact on its way in the next 15 minutes or so. And since that timetable can be a little wobbly where punctuality is concerned (not for lack of effort by HART, but due to accidents and traffic conditions inherent to a bus system in general), such a system is ideal to tip you off that a bus is running a little late or that you have already missed it. You can use this information to precisely decide when to leave a house or business, or, whether to spend a few minutes more browsing for clothes, sipping coffee, or, yes, even consider making other transportation choices for that particular trip if need be. I've poked around with this and it seems you can even set a reminder for a particular bus so that you get dinged when it gets feasibly close enough for you to go meet it. It's just awesome.
The other reason is that summer weather in Tampa is volatile with its deadly lighting storms. Everything I wrote above is even more crucial when gambling how long you're going to risk standing out on the side of a road next to a bus-stop-sign-turned-into-a-lightning-rod, or taking the chance to reach it. That is if you calculate that risk at all...I never would (meaning, I never go outside during a lightning storm period) but I know that many people do.
Most of us who hear the words "GPS" and "transit" immediately conjure thoughts of a map with buses or trains that blip on and off as little icons visually detailing their exact location much like the USF Bull Tracker system does. However the new system by HART does not yet go this far, although does not need to in order to present quality real-time arrival information. The current system is most likely a precursor to a deluxe one but you won't have to wait for it to enjoy the benefits of tightning up your transit, and therefore your personal schedule, today.
Note that the when downloading for your device (i.e., iPhone or Android phone) it is best to do so directly through the device itself. Visit the app store and search for OneBusAway.