I use Outlook for work (the Exchange version, not outlook.com) and would like to see WP8 bring over more of it's mail and calendar features. Categories, follow up options, ability to set priority level, bold and italic fonts, better attachment functions- these would all be welcome.
Also, I'd like to be able to set up toast notifications for select people or topics, or high priority mail. I get lots of email so I wouldn't want continuous toasts. But when a high priority client email comes I'd like to know that immediately.