Here's a tip to change the stock "cheese grater" dock on an iPhone. Of course you can use Winterboard and any number of themes to do this. I have found the current version of Winterboard on my iPhone 3G to have too much lag but really wanted to change the dock. Of course installing shiny dock does nothing to change the icons, black blackground, etc. It does change the dock without using Mobile Substrate or Winterboard. I found Shiny Dock when I installed All Sources. An easy way to get it is to just install this repo in Cydia:
http://c.ifon1.no/
Then install Shiny Dock
http://c.ifon1.no/
Then install Shiny Dock