Although the Canon Pixma MP160 printer works fine in Ubuntu 9.10, it however does not want to print correctly margined envelopes using OpenOffice 3.1.1.
Boy was I pulling my hair out for a bit... until... I plugged in my HP Photosmart 8049, another printer to test with. The second try with the correct margins and using the pulldown menu for #10 envelope type, I was amazed it actually worked without fussing around with values. Woo hoo!
So don't go crazy trying to make the Canon Pixma MP160 printer work with OpenOffice envelope printing on Ubuntu 9.10 unless you have tons of patience; which I do not.. If, however, you get envelopes working with said printer, please share!