Comment 3 for bug 114565

I can confirm this problem on gutsy: garmin_gps claims device and make USB device not usable.

related dmesg output:
[12128.336000] usbcore: registered new interface driver usbserial
[12128.340000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c: USB Serial support registered for generic
[12128.340000] usbcore: registered new interface driver usbserial_generic
[12128.340000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c: USB Serial Driver core
[12128.348000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c: USB Serial support registered for Garmin GPS usb/tty
[12128.348000] garmin_gps 2-1:1.0: Garmin GPS usb/tty converter detected
[12128.348000] usb 2-1: Garmin GPS usb/tty converter now attached to ttyUSB0
[12128.348000] usbcore: registered new interface driver garmin_gps
[12128.348000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/garmin_gps.c: garmin gps driver v0.28

Since most of newer GPS devices are USB and latest SW releases (gpsbabel, QLandkarte) supports USB devices directly (through USB device instead of tty), we should blacklist garmin_gps module by default. This should be done by changing /etc/modprobe.d/blacklist.
There are many websites/blogs documenting this issue (you can find them via google).

It would be also great if we could have proper udev rules to create device files with proper permissions (0660 and group set to plugdev) in order to work out of box.