I spent a whole day solving the issue that adb can not found my g1 phone.
Tried setting udev rules, using root, still no luck.
Googled a lot, came to a webpage talking about `screen capture’, which mentioned that you need to set `USB debugging’ on.
So, go to Applications -> Development -> USB debugging, set it on.
Then, as normal user, without udev rules, `adb devices’ finally told me he found a device attached. Wow.
`USB debugging’ is set on by default, I turn it off few days ago. Shit.
That’s it. In case some guys come into the same problem, hope this may help.