Edit2:
Here is a nice vfu shortcut overview:
https://help.ubuntu.com/community/Vfu
/Edit2

Did you notice that <Enter> doesn't work in vfu? It's not a tragedy if you have lynx-like motion activated but it would be better if it worked.

I had a look at the vfu sources and it sems to me that vfu checks the ASCII code a key generates and if it's 10(d) or 13(d) the Enter routines are executed. For some reason Maemo (hildon?) does not seem to allow/create that ASCII code.
I tried your vfu package, mine and the standard Debian package via debbie. With none of them <Enter> works. But if I run vfu within a fully loaded Easy Debian on the N900 Enter works and according to xev it creates the ASCII code 0d(b) which is 13(d). I ran xev via debbie to see what happens in Maemo but here I get no reasonable output in xev on key press events at all.

Do you have any idea what's going on there?

Edit:I'm aware that the key on the N900 keyboard is <Enter> and not <Return> and that both create different keycodes. But they create the same ASCII codes according to xev on my laptops And the N900 <Enter> works fine fot vfu in Easy Debian so I'm pretty sure this is not the problem.