From the "just for fun!" department: Full version of Mac OS X 10.3 running on the N900! I believe this makes the N900 the first smartphone EVER to run the full version of Mac OS X (at any speed, slow or otherwise). Youtube video below.
As you can see from the heavily edited video, it took almost 2 hours to reach the "About my Mac…" window. Keep your eye on the time display as that will give you an impression of just how uselessly slow it is. The emulator I used was the latest CVS snapshot of PearPC, which to my eye appears to be pretty good quality code, built without problems in Scratchbox. I experimented with the various frontends and finally settled on the SDL one, since support for the mouse cursor seemed to work best there. As in my previous emulation attempts, I used x11vnc to remotely control the mouse from a laptop sitting nearby. And once again the screen size of N900 was slightly too little to run something that expects a desktop-size display.