I did as soon as I read your message and, WOW, the driver has improved a lot! Now camorama does not lock up (although it shows a triple image) and permits changing the settings (brightness, contrast etc.) and camstream shows the image as mplayer. However, the image is incredibly dark, and I couldn't even see anything if I didn't point it to the lamp of my room. You can see how it appears here:
http://patola.org/lamp.png
Best regards,
Cláudio
P.S.: dmesg--
[ 2275.784507] usb 1-2: new full speed USB device using uhci_hcd and address 3
[ 2275.978342] usb 1-2: configuration #1 chosen from 1 choice
[ 2275.995851] gspca: probing 0ac8:307b
[ 2277.620607] zc3xx: probe 2wr ov vga 0x0000
[ 2277.739151] zc3xx: probe 3wr vga 1 0x4001
[ 2277.827007] zc3xx: probe 3wr vga type 29
[ 2277.831000] zc3xx: probe sensor -> 29
[ 2277.831005] zc3xx: Find Sensor GC0305
[ 2277.832175] gspca: probe ok