Hmm...

So I use the iGo and type, type, type...

Close the iGo, wait until the blue tooth symbol turns white - maybe 10 seconds - tap into a text area and up pops the on-screen keyboard.

It seems to just work without un-pairing and re-pairing, no fn. keys - just fold it away. I was quite impressed the first time I used it ...

This is on the original N800 OS2008, I have not updated yet.