most of you will remember that iOS 3.x zoomed in far more when the screen was tapped twice with 3 fingers. however, currently, with iOS 4.x the zoom is just barely noticeable.

so for those of you that are jailbroken, you can have the same amount of zoom which was in 3.x or greater by editing

com.apple.ZoomTouch.plist

it's located in var/mobile/preference
the plist will read

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>ZoomLevel</key>
<real>1.2166666984558105</real>
<key>ZoomLocationX</key>
<real>160</real>
<key>ZoomLocationY</key>
<real>240</real>
<key>Zoomed</key>
<false/>
</dict>
</plist>

edit the numbers within
<key>ZoomLevel</key>
<real>1.2166666984558105</real>
and you will have a greater zoom on the screen.
mine is currently set to 3.2166666984558105
and i have a far greater zoom on the screen when tapped with 3 fingers.

nothing too great or life changing. just a fiddle here and there