Not a complaint, not a moan, just an observation having used iPhone Explorer.
I used to use iPhone Explorer on 4.3.3 (non Jailbroken) to change the icon artwork on apps which had been left, lazily, untouched to make them look good on the Retina Display.
It annoys me having gritty, pixellated icons amongst the high resolution ones, and there's no excuse for it given that iTunes shows high resolution artwork for all app icons, even on the App Store ON the iPhone!
On 4.3.3 you can go into iPhone Explorer and change the icon.png file for a 175x175 (or 512x512 if you like, the phone resizes it regardless) image. High resolution icons for most apps can be found with a Google search, and I updated the likes of GTA Chinatown Wars and Sonic 4 with high resolution icons. I liked this because I used to jailbreak to use iRetiner GUI to make all non-Retina adapted icons use their App Store counterparts instead. I don't like being jailbroken though, so iPhone Explorer was ideal for this "issue".
On iOS 5 Beta 1, you can browse the iPhone no problem, find the icon.png and even replace it. However, when you reboot the iPhone, the old grainy artwork persists, despite you replacing it with a higher resolution one. Weird, but again it's only a Beta so I'm not complaining, just giving people a heads up.