I just have to add this everywhere the idea comes up: Having folders is a must for an application launcher, no matter if its Maemo's default applications menu or a third party app.

But:

If you think of folders, please also think of the way they are implemented correctly, following the freedesktop.org standard: as catagories in the .desktop-file of an application. (The user is free to change these default locations, of course, but it's a good start.)

Whatever work is invested in this area should, I think, re-use things that already work and that people (developers, in this case) are familiar with.