Zephyr by chpwn has been updated to version 1.0.2-1 with a few more enhancements. For starters, you can now disable gestures in any app you choose. This is handy for games and apps that may cause you to unintentionally invoke a gesture. It looks as if he's gotten help with this feature from Ryan Petrich, creator of Display Recorder, one of my favorite jailbreak apps.
Other features added include the ability to enable per-gesture commands as opposed to them all being global by default. So if you want multitasking gestures on your iPhone, you can find Zephyr in Cydia for $2.99.