Speaking at a Gartner event in Florida today, Ballmer said "iPad will be picked up when there's a touch first user interface." That touch first interface appears to be making its way to the Windows version of Office first, with the iPad edition to follow afterwards. Ballmer noted the touch first interface is "in progress." Microsoft has previously released an Office version for iPhone without support for the iPad, noting at the time that tablet users could make use of Office Web Apps in the browser instead.
The site also learned that Microsoft's head of application and services, Qi Lu, said that the company is "working on touch-first versions for our core apps in the Office suite" at a recent meeting. The plan is to "bring these apps to Windows devices, and also to other devices in ways that meet out customers' needs."
Currently, Microsoft has only released Office Mobile for iPhone to customers with an Office 365 subscription.