How can I print e-mails landscape from Outlook 2010? Maybe I'm missing something but from the Print dialog in Office 2010 (OS X 10.7.3) I can't find where to set orientation?

It doesn't appear under Outlook, Layout, Color Matching, Paper Handling, Paper Feed, Cover Page or Printer Features.
This works in Entourage 2007 so I'm assuming that it work on Outlook 2010.

Try File > Page Setup then select Landscape. Or File > Print... > then select "Layout" > and change it Landscape.