As you are most likely aware, Microsoft announced the Office 2013 and SharePoint 2013 preview on the 16th of July. There is already a stack of information out there but if you are getting started or want to find out more here is a summary of some of the resources I’ve found useful:
Office 2013 Launch Event and Overview
A good place to start is the webcast of the official Office 2013 launch event from Microsoft. If you prefer reading rather than watching the Engadget article Microsoft Office 2013 preview: details, screenshots and impressions gives a good overview of the Office 2013 features. Some of the big changes are that Office has been redesigned to work with touch devices and integrates heavily with the cloud including SkyDrive and Skype integration. Microsoft also has details on the Office application updates at http://www.microsoft.com/office/preview/en.
SharePoint Developer Center on MSDN
The SharePoint developer centre on MSDN has a good overview of the new developer related features in SharePoint 2013 including 18 training videos on new functionality relating to the changes in search, social ECM, WCM, REST, App development and OAuth.
Understanding SharePoint 2013 Apps
A big change for developers in SharePoint 2013 is the introduction of SharePoint Apps. Andrew Connell has a great overview of the new SharePoint App Model and how it fits in with other development options in his article Understanding SharePoint 2013 Apps (aka: Apps 101). While you are there be sure to register for their upcoming SharePoint 2013 webinars.
Start building apps for Office and SharePoint
To find out more about developing apps there are some great resources at the Apps for Office and SharePoint site, including code samples, details on the ‘Napa’ Office 365 Development Tools and detailed API documentation.
Sign up for an Office 365 Developer Site
The quickest way to get started building apps is to create a Office 365 Developer Site which gives you a preconfigured SharePoint 2013 Preview site. Sign up at http://msdn.microsoft.com/en-us/library/office/apps/fp179924(v=office.15) – within a few minutes you will have a shiny new SharePoint 2013 site to play with!
Download Microsoft SharePoint Server 2013 Preview
If you want to get the on-premise version you can grab it from http://technet.microsoft.com/en-US/evalcenter/hh973397.aspx?wt.mc_id=TEC_121_1_33. Eric Harlan has a good article on How to install SharePoint 2013 but this is largely the same as SharePoint 2010.
SharePoint 2013 TechCenter
To get an understanding of the architectural changes including an overview of enterprise search and authentication head over to the SharePoint 2013 for IT pros site on TechNet. This includes a bunch of videos and presentations covering the new SharePoint 2013 functionality from search (FAST functionality is now baked into the core search component), architecture, mobile, authentication (Claims is now the default and Classic mode has been deprecated), WCM (including the new Content by Search Web Part) and much more.