I checked apple discussion board for ipod touch saw many wi-fi questions. So I thought this is not a trick but it is a tip on how to setup your ipod touch for wireless.
First ask your self do you have secured or unsecured wireless connection?
1. Go to Settings
2. Go to Wi-FI
3. Click on Your Wireless
4. Punch in your WEP key
5. Connect to it.
If NOT Secured
Follow all steps above except no.4
If you have problems connecting with your Ipod touch to your wireless please comment bellow and I will resolve your issue by answering as well. Or email me ilovetoargue at gmail dot com
UPDATE 09/11/2009: Please check this post:
Great Tutorial by MWD
Ipod Touch WiFi (Wireless Troubleshooting) Part 2
Ipod Touch Wireless Problems
Visit Ipod Touch Forum For Troubleshooting WiFi - Post Question and get answer by others and me as well.