Notices

There are several alternative keyboards replacing default virtual keyboard of Maemo 5: to enable portrait mode, handwriting recognition, T9 input, or something else. However, after installing one of them, in order to enable it as the virtual keyboard used by the system, user had to type gconf command in X-Terminal; it's not exactly user-friendly, it doesn't show which keyboards you already have installed, it allows possibility of misprint, et cetera.
This simple Hildon Control Panel applet adds an entry ('Select Virtual Keyboard') to Settings window. It shows, in a dialogue, selector with list of files any of which could be used as a virtual keyboard. When the selection is changed, a banner (yellow strip) shows information about the currently selected file: name and description of the package to which it belongs. If the dialogue is dismissed, virtual keyboard is not changed. If the ”OK” button is pressed, virtual keyboard is set in accordance with the selection.
The package was uploaded to Extras-Devel with gracious assistance of Maemo Extras Assistant. It can be installed by ”apt-get install virtransim”, for instance, since the name of the package is ”virtransim”. The icon has been recently created. The most recent version is 0.1.3. The last version tested on the device is 0.1.1. Considering that the N900 it was created on is not working now (hardware problem), beta-testers and any feedback would be welcome. Does the latest version work at all? What icon does it show in the Application Manager? Does it have its icon visible in the Settings window?
[EDIT]
Version 0.1.3 has just been tested. A screenshot of the Settings window is attached, with the icon visible.
[/EDIT]

I just checked the version from yesterday and it seemed to work ok for me.

Nice and useful. Could you comment which virtual keyboards have already tested with it?

Thank you. I am participating in the 2012 Coding Competition, and positive vote is appreciated.
I have tested the applet mainly by switching between default virtual keyboard and him-cellwriter. It also allows to make, for instance, "special characters" keyboard, the onscreen keyboard - though it may seem impractical, it is also a virtual keyboard, and thus eligible for being listed in the selector. I haven't used him-cellwriter much - it's neat, but I didn't have the patience to train it fully, and I was mostly using the hardware keyboard for typing.
No virtual keyboard should have any problem with this applet. When a keyboard is set, by user pressing "OK" button, the applet is doing the same as typing "gconftool-2 --type string /apps/osso/inputmethod/default-plugins/finger -s short-filename-without-extension" in X-Terminal would have done.
What's the difference between keyboard-triggers 'finger' and 'stylus'? As far as I have noticed, no applications behave differently for finger and stylus. Yet, /apps/osso/inputmethod/default-plugins/finger and /apps/osso/inputmethod/default-plugins/stylus are separate from each other. Yet, the same onscreen keyboard is used for both finger and stylus, as if the system always default to 'finger'.
Feedback and screenshots are welcome.

You could also add a button to force showing the virtual keyboard. This would address some concerns raised by freemangordon when using portrait keyboard.

TBH the next thing that comes to my mind besides proximity detector is power key menu.

Then you have this.

Not really off-topic (it's better than starting a new thread).
I have done a quite thorough search and I cant find a definitive answer to my question. Is/are there working portrait vkb(s) for the N900? If
so, which is the best one?

Promise to delete this post when I get a useful answer.

There are several working portrait vkb(s) for the N900... Read, look at screenshots and decide.
Chinese Input Method: QML-based Virtual Keyboard,
mcip - a Virtual Keyboard in QML
Finally: Auto-rotating, QWERTY and T9 virtual keyboard in all applications,
portrait-keyboard.
I am also curious about nemo-keyboard, but I don't know whether it works properly on Maemo.

Where would you like the button to be placed? Or what trigger would be best to use? Would it be suitable if double-tapping the device would bring up the virtual keyboard? The accelerometer's ability to detect double-tap is not used at all, as far as I know.
It would probably be a separate application/package, and I doubt it can be written in time for the deadline. Unless there is an easy-to-find example of code to force the virtual keyboard to be shown, and I haven't seen it yet.
Edit: hildon-input-method can give code how to force virtual keyboard to be shown. So, what should be the trigger?