This is a small guide to recover the gesture pattern of your android phone.

You'll need (temporary) root access to the filesystem of your phone. This can be done by booting a recovery image using the Android SDK. Installing the SDK is out of the scope of this guide, but there is plenty of help available on the internet to do this.
First, connect the phone to the computer using the USB cable.
If you have rooted your phone, you can get the gesture file directly, otherwise, boot a recovery image with the SDK fastboot tool.
It is a bit tricky to find a working recovery image on the internet, but you should be able to find cm-hero-recovery.img (for the HTC Hero, other phones have other recovery images) somewhere.
Get your phone into "Fastboot USB" mode, this is different for every phone (on + back on the HTC Hero).
The command to boot the recovery image is: 

fastboot boot cm-hero-recovery.img
When the recovery image is loaded, you can use adb to get the gesture key.
adb shell mount /data
This will mount the /data directory (the recovery image might have skipped this step).
adb shell od -x /data/system/gesture.key
This will display the unlock hash (the first block on each line is not part of the hash).
0000000
0000020Paste the parts here to get te unlock gesture.

This is your unlock gesture: