checkout the hostmode mod (h.e.n.) and make or find a usb adaptor cable so you can use a cheap usb SD card reader so you can transfer photos from the SD cards to the N900.

Have Upload working to several different sites/services (picasa, flickr, wordpress blog etc). Also email them to at least a couple of good long term friends, after asking them to keep them for you. then if you lose access to one account for any reason, you still have copies

Nothing worse than doing a trip and then losing the photos. I did 11 years ago when digital was in it's infancy.

And test? dry/run it all before you go, so you know it works and how it works.