Microsoft Office will eventually come to iPad, according to none other than Steve Ballmer. It's probable that the iPad version of Office will follow a touch-based version of the app suite for Windows 8. But it appears that we may be waiting for Office on iPad for a bit longer, according to The Verge:
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 released Office Mobile in June for Office 365 subscribers, letting users create and edit Office documents on an iPhone. Whatever form Office eventually takes on the iPad, it will no doubt also require an Office 365 subscription to use. And while we don't know when Office will appear on the iPad, it has been rumored that late 2014 is the targeted launch window. Unfortunately for Microsoft, that might be too late.