Point of interest, Ctrl+Backspace on the N900 will bring up the task switcher from (virtually?) any context, so if you have the keyboard out, it's actually arguably quicker than the N810's method. But yes, I miss some of the hardware buttons, too. On that note, @OP, I forgot to mention that the completely useless (and uselessly-located) lock switch on the N810 has been replaced with a wonderfully springy tab that you can easily flick with your thumb as stow or retrieve the phone from your pocket/purse/gadget holster. Also, it actually blanks the screen right away, rather than leaving it on until it times out, like the N810.

Yes, another point I missed - the N900's touch panel is superb. It's probably the most sensitive resistive panel I've used, although admittedly my experience isn't that broad. It is certainly much better than the N810's, and the flush mount means you don't get cruft around the edges of the bezel.