GTK libs are part of Maemo, yes. Maemoizing gHamachi would probably take quite a bit of time --- re-organizing the UI and such.

With the amount of effort that would take, and given my personally modest needs, I'd rather code it up as a status bar plugin supporting start/login and logout/stop only.

Setting it up via the command line isn't -too- bad, it's just bringing it up and down and checking the status, for me