Wow - thanks for the quick reply. I already do what you suggest - but then I get the usual "fixed size static layout" of the PDF, which is not always nice. After a month using my kindle, I've been converted to the "reflow for the people" movement!!
I was thinking as the "printer driver" more as a metaphore - it would be nice to have a "save as mobi/epub" option everywhere, and since "print" works in every application a printer driver could be a hack.
Does this make sense?