Nothing but love for the lightly-updated iWork, but millions of Macs in SOHO, business and enterprise settings depend on Microsoft's Office 2011 suite for productivity mojo every day. The Office for Mac team noted on its official blog that Office 2011 is Mountain Lion-ready and fully supported, as is (somewhat surprisingly) Office 2008.
The O4M team offers up two quick tips for making sure Office 2011 is current. First, check that the AutoUpdate feature is enabled & run any available updates; you can find AutoUpdate by going to the Help menu in any Office app and choosing Check for Updates.
Second, it looks like the standalone Office updater packages you can download from the O4M site will not play nicely with Mountain Lion's Gatekeeper binary signing, at least not with the default security settings in place. The recommendation is to use AutoUpdate (which is signed) to run any necessary Office patches.
Regarding Gatekeeper (which we'll talk about more later today), two quick reminders: Any application that is on your Mac at upgrade time is automatically marked as OK to run under Gatekeeper and does not need to be a signed binary. Also, you can bypass the Gatekeeper settings on an app by app basis -- without switching your whole system to the less-secure mode -- if you right-click/control-click an application icon and choose Open, that opens a dialog for "whitelisting" that particular app. Once you launch it once, it will be OK in perpetuity.