The thing is, if the SD Card write protection notch is down, then well, Linux will cry because it can't write anything to the SD Card as it's read-only. Although, if you dd directly (forcing a bypass of the switch) to the SD Card device, let's say /dev/sdcard0, you can write anything on it.
What I do on Plug Computers is this:
Before first boot - Plug the SD Card into a Linux PC. Edit the SD Card Linux /etc/fstab file something like:
none tmpfs /var/log defaults,size=16M 0 0
Repeat for other temporary caches that linux might use (/var/run, etc). That way, what happens is that linux boots, it'll write all the boot logs to a RAM Drive and save a few dozen write cycles on the SD Card itself. When the Pi is switched off, the dmesg logs etc are cleared.
Another method to do that but make tmpfs areas for all the parts where Linux needs to write to (/var/log, etc) and then mount the root partition read-only. That way, Linux can still read/write, but changes will only be made in memory.
When I get a Raspberry Pi for my tablet PC project, I'll most likely use a big loopback file called userdata.img where I'll mount /home/user on it. If the user botches the image file up, no worries, I'll have a recovery process in there that will recreate a fresh image file.