Uh, what the hell? Had Uber already learnt the lesson the last time? There were already previous blog posts and articles about Uber causing some security or other controversy that there were some complaints coming in from the customers and various organizations and yet they're planning to invade Outlook with their service? This is all happening at this year's BUILD conference organized by Microsoft in which there will be new features and improvements for Windows 10 and the new prototype stage is now Insider Preview which I'm already using under Slow Ring mode. Don't use Fast Ring mode no matter what as it already annoyed the hell out of me when prototyping Windows 10 as if you may end up cursing and swearing at the OS when broken things happen.
The deeper Cortana integration will be coming in summer. Previously, you could use Cortana to request the Uber car via the app or something but with Uber add-in for Outlook, you can make similar requests based on your Outlook calendar.
If Uber is already doing things right this time, then the customers will have less problems making requests for Uber cars in the future.