You slide the latch to expand and power on the G1. It doesn't open completely in one go, however; after about three-quarters of an extension, you must reposition your hand and exert a little more effort to open it all the way. The whole process exacerbates the already long (over 4 seconds) time to first shot. You don't have to close it completely, though, and can use the power button instead.
To connect directly with up to three other G1s, you press your WLAN buttons simultaneously.