Mac OS X Virtual Machines
Several, non-Microsoft/non-Azure, cloud-hosting services offer either dedicated, or virtualized machines running Mac OS X (with the OS running on Apple hardware, due to Mac OS X licensing). Examples include http://macstadium.com/, http://xcloud.me/, and http://www.macincloud.com/, among others.
Being able to provision a Mac OS X machine on Azure, using Azure pricing, and potentially, Azure Virtual Networking, would be useful for developers wishing to set up build machines for iOS apps, and potentially other use-cases.
This is not something that we have on our roadmap. It is something that we may consider in the future.
David Ludwig commented
Alternatively, if this were made available, and a larger cost were necessary (as is the case with many Azure VM types) in order to cover costs of Apple hardware, that'd be fine. Regarding "Azure pricing", the thought there is to make OS X VMs available through one billing provider (Azure).