Works fine for me. Tested with an iPod Video and an old (full-speed!) Fujifilm SM-R2 SmartMedia reader (that's that enormous memory card format they've stopped manufacturing). Both mounted and could be read.

The black cable in the photo is from this eBay UK page (presumably, the eBay pic is actually two of them). It is slightly shorter than the N900 itself, but still flexes enough to prevent it acting as a lever to break the USB socket.

This cable definitely seems like a very portable alternative to a rigid, socket-breaking adaptor, and is available in the UK.

(Sorry for the poorly-lit webcam pic... white cable is just a regular A-B cable).

Initially, the camera didn't work with Titan's kernel (I use FCam).
followed by a reboot fixed things. I haven't checked, but I believe that fix requires extras-devel.

Thanks to everyone who made hostmode work!

P.S. It appears that that international seller sells the same adaptor on ebay.com too.

Edit: Tried a Logitech mouse and an A4Tech KL-5UP keyboard with extkbd - both worked fine (this is a "slim" keyboard with no numpad - I actually wouldn't mind taking this on a train if I had some LaTeX to write on the N900).