I've been using something called NemusSync on 1.1.4 JB. One of the reasons I'm hesitant to upgrade is because I don't want to lose Nemus. It's not push, but with one touch it syncs your iPod touch cal with google cal, both ways. In other words, events you enter on your iPod get uploaded as well as events from gcal downloading. If you have multiple calendars in gcal, you can indicate which calendar to upload your iPod cal events to.
Then when you sync your iPod to your computer, it updates your computer cal with all the gcal events on your iPod. It's awesome, it's my main reason for wanting to stay jailbroken.