Here is the quick and dirty truth. They all do the same thing! There is very little difference between the data packages. The only real difference that I can think of off the top of my head is that Smartphone Connect cannot access Cingular/Cellular Video (at least it couldn't when I got my Blackjack

.)
When I was working for Cingular they broke it down like this. Depending on how data centric your handset was is what determined your data plan. I personally use the Media Max 200 data plan which gives me unlimited data and 200 SMS a month. Since my Blackjack has a keyboard on it and push email, Cingular figures I would use a lot more data then someone with a Motorola RAZR or Cingular 2125 therefor the stores try and stick you on the $39.99 PDA Connect plan.
Now I know what you're thinking, "Cingular is trying to rip me off!"
The truth is, the people who determine what features go to what phone are so out of touch with the products they sell that they do not know the difference between Windows Mobile Standard (Smartphone) and Windows Mobile professional (Pocket PC). They just see the device has a keyboard so it must be one of the devices that require the higher up data plan. You have no idea how many friendly, yet heated, arguments I have been in with a few friends of mine in the Cingular corporate offices here in Cingular on the same subject.
