Not sure you can get to hidden folders with the graphical file managers, but Midnight Commander (mc) on the terminal interface will do it. I suspect that when we get to discussions of hidden folders under Linux, we're talking about command line stuff. Being a *nix sysadmin, this never occurred to me. I would just jump in the terminal app, and do what I want directly.

Note: Under OS2008's repositories, I do not see Midnight Commander. I did install it from a repository last time, so it's entirely possible you can go to Maemo's Web pages, and the OS2007 version will install, and work.