I do not yet have a device so this is speculation on my part; I do not think there is any encryption software on the device. You can get ccrypt (I saw a posting on this forum for a binary the other day) along with pgp/gpg BUT this means you have to edit in plain text, then convert to encrypted, so at some point you have plain data written to "disk" :-(

The password safe port(s) you've seen are probably your best bet for a while. I am in the middle of working on a plain text notes program that has built in encryption support (that is compatible with the Windows Tombo program) but it is not really ready for prime time yet. Because I do not have a device I've not even tried to Hildonize it yet. If you like hacking Python you could check out http://code.google.com/p/pytombo/wiki/GtkTombo, the code is in subversion. Here is a (Windows) screen shot



Again this is pretty much vapor ware as far as end users are concerned but for (python) developers they may find something useful.

Chris