Just in case you were wondering, add-ins for Office function in a similar manner to that of browser extensions, and this move by Microsoft is definitely a boon since they happen to be available already on Windows, the iPad and the online Office interface, so to have Mac users jump on board makes it all the more cohesive when one wants to be productive across multiple platforms and operating systems.
Not only that, Microsoft has also introduced new tools that will assist in the construction of additional advanced Excel add-ins, to be able to deploy Office add-ins assuming one happens to be a system administrator, and to hunt down add-ins for Outlook. Heck, there is even a new Starbucks add-in that was shown off, letting one send gift cards to your contacts from the email app itself, as well as the ability to schedule coffee meetings which will sport links that allows one to place their orders before the meeting even starts! [Press Release]