SharePoint 2013

SharePoint 2013 Preview sites provide secure environments that administrators can configure to provide personalized access to documents and other information.

Download SharePoint Foundation 2013:

http://www.microsoft.com/en-us/download/details.aspx?id=30345

The current model is actually quite good. It helps make the development and deployment process much easier, as the entire solution can be packaged within a solution file. The solution can be upgraded quite easily, and sandboxed solutions are a great way to pilot new code or deliver unique experiences in a multi-tenant environment, like Office 365.

Microsoft has already published a very detailed documentation on this and here are those which can be useful for your reference:

Downloadable content for SharePoint 2013

http://technet.microsoft.com/en-us/library/cc262788(v=office.15)

Video demos and training for SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc262880(v=office.15)

Technical diagrams for SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc263199(v=office.15)

Explore SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc261970(v=office.15)

Plan for SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc261834(v=office.15)

Develop for SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc262356(v=office.15)

Install and configure SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc262957(v=office.15)

Use SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/fp123457(v=office.15)

Troubleshooting SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/gg609831(v=office.15)

Technical reference for SharePoint 2013 Preview

http://technet.microsoft.com/en-us/library/cc262798(v=office.15)

Scenarios and solutions for the real world in SharePoint Server 2013 Preview

http://technet.microsoft.com/en-us/library/ff872147(v=office.15)