The ASU and 2007.2 Openmoko distributions have been designed to bring up an on-screen keyboard which supplies keystroke information to applications. However, this requires the cooperation of the application, which is a problem for software designed with another X11 based phone stack in mind, or software which has been quickly ported from Linux desktop systems, because it will never bring up a keyboard for (possibly important) keystroke information. It is also possible that the keyboard could be brought or remain up by accident when you don't want it there, or even software specifically designed with this functionality in mind may occasionally fail or become confused when an on screen keyboard is supposed to be available.
Alternatively, you can try connecting a bluetooth keyboard or USB keyboard (Only available with a special cable, or an extra special cable in the case of the older unpowered USB units.)
Reactivating the keyboard toggle under ASU
On the phone
Install the tools required to decompile and recompile E17 theme code.
opkg install libevas-saver-png edje-utils cpp ln -s /lib/cpp /usr/bin/cpp
Decompile the theme, and edit the edc file
cd /usr/share/enlightenment/data/themes/illume edje_decc illume.edj cd illume vi freerunner.edc
Search for the text 'qwerty'. This should take you to the section which defines the small 'qwerty' button in the upper left, which has been disabled by the developers with a 'visible 0' entry. Comment it out, and replace it with 'visible 1'. Then rebuild the theme.
Building a custom package
If that doesn't work, follow the instructions on building ASU from source. Unpack the source for the package 'illume-theme', edit its edc file using the same method described above, and then finish building the ipk. You should be able to install this ipk, overiding the previous configuration.
If you upgrade, such as with opkg upgrade, you may have to perform the modification again.