I've noticed lately that at random intervals I will lose the data connection on my phone. I can be using the browser and then at random intervals it won't be able to load a page. The 3G remains the same and I have full signal, just do data transfer.
Also (not sure if discussing this part is allowed or not) but during wifi tethering I also notice that the data transfers will stop at random intervals. I use the wifi tether for an iphone4 (using it as an ipod basically) to be able to stream netflix shows. It will work for a while then just stop randomly. I've tried both Barnacle and the Wifi tether and it is the same with both.