Thankfully, I won't have to answer this question. I went to look carefully and there, tucked away inside just out of sight (threatening to go deeper into the machine) was the magnet! I pulled it out with tweezers, re-mounted it and voila, I 'have' an internal memory card again!

[rant]

Now, I love my N800, and I've been careful about how I criticize the product because I do believe in it so much, but I have to say, this is one of the very worst design flaws I've ever seen in any product.

What logical reason can there be for disabling the sd card when the little magnet is not in place? What is the function of the magnet? To hold the cover or 'enable' the SD card?

This is a serious usability issue, and it makes me wonder who was in the hardware specs review meeting where someone said,

"I think we should make it so that if the magnet on the back cover isn't in contact with the circuit board, then the internal SD card should be inaccessible. After all, it has to be that way because...."

Right. Engineers. I do hope this 'feature' hasn't been 'continued' in the N810

[/rant]