Yup it's for an older kernel, but the guy has to be given credit.

I sometimes ask this on the irc channel too, but there don't seem to be enough developers involved in this right now.

The N800 does have an OTG (on the go) chip which supplies around 100ma, enough for a keyboard, pen drive, UART-USB adapters(which is what I'm after since the N800 does not have any serial ports).You can see the specifications on thought fix's blog.
http://tabletblog.com/search?q=otg

There is one UART behind the battery cover, but that gives startup roll information at boot time. Theres no /dev/ttyS0.

One way is to use bluetooth Serial Port Profile. But the adapters are like $70 plus compared to a $20 around USB Serial adapter...And the kernel has builtin drivers for it too.

And as you said.. apart from my needs, host mode for external flash memory.