Hello,
I also have the problem with the plugin crashing calibre when selecting any option in the kobo utility menu when my kobo glo is connected.
Im running calibre 0.9.35 on os x 10.8.4 with the beta4 file from earlier in the thread. My Kobo is running firmware version 2.5.2.
You can have a look at the crashlog
here
Hope this helps!