The event itself is being held in Washington DC and, as with previous WPC shows, it gives Microsoft a forum to reveal its immediate future plans to its many third party partners. This has become especially important this year thanks to Nadella's long email to Microsoft employees last week, where he offered up some general information on the company's new "mobile first, cloud first" agenda, along with hints of some major organizational changes that will be made soon.
We don't expect Nadella to offer a lot of specific information about those changes during his WPC 2014 keynote, but it's possible he could offer some more hints about what is to come. Microsoft will also likely use the keynote to give an update on the sales of some specific products, such as Windows 8/8.1, Office 365, and more.
Microsoft is offering a live stream of the WPC 2014 keynote speech and we will offer updates if anything major is revealed during the event.
Update: It looks like Nadella won't actually be speaking today, but he will be attending the conference on Wednesday for the event's second keynote.