I have ported the iCountDown app to firmware 2.0
The original project is at
http://code.google.com/p/icountdown/
The program will run on firmware 2.0 and you can just put the folder iCountDown.app after unzip (sorry no installer at this moment) to iPhone's folder /Applications/
This has been tested on iPhone firmware 2.0 beta 3 (pwned)
MD5 (iCountDown.zip) = b59732e853a7d3bb1171b1dbb49ef724
To install, type these commands in Mac OS X Terminal ssh session/ Putty (windows)
wget http://www.iphone.org.hk/attach/29053-iCountDown.zip
unzip -oj 29053-iCountDown.zip build/2.0/iCountDown.app/* -d /Applications/iCountDown.app
If you don't have wget in iPhone, get it from here, this wget binary works in firmware 2.0
http://ericasadun.com/ftp/PortedUtilities/
29053-iCountDown.zip