SharePoint 2010 SDK is out in a primary version. You can get it here: http://www.microsoft.com/downloads/details.aspx?FamilyID=94afe886-3b20-4bc9-9a0d-acd8cd232c24&displaylang=en
Right now it contains API reference, along with a white paper for how to customize the ribbon.
Ribbon customization is done using features that use the CustomAction command. nothing special here.
Going through the API reference I have discovered some very interesting stuff. My favorites are:
- JSGrid web control – I take that for JavaScript grid.
- Microsoft.SharePoint.Client Namespace – seems like a trimmed down version of the OM that’s available from client side.
- SPList.DataSource - “Gets the data source for a list that has an external data source.”
- Chart control - “Represents a chart control for use with Microsoft SharePoint Server 2010 farms that use multiple front-ends, and ensures that the user who rendered the Web page that contains the chart is the only user who can download the chart image.”
Sounds great! I particularly liked the client side aware approach with 2010.
P.S. thanks to Elad Khalo for the heads up.