Microsoft has partnered with the folks at http://www.symbolsource.org/ to offer a really simple way of publishing your sources and PDB’s along with your NuGet package.
Up until now, there really wasn’t a great way for package authors to let their users debug into the package’s binaries. The user would have needed to download the sources separately from wherever the project is hosted, making sure that they exactly match the state of the binary. They would also need to locate the matching PDBs. That’s pretty hard to get right, and most users would generally not bother.
Now with almost no additional effort, package authors can publish their symbols and sources, and package consumers can debug into them from Visual Studio.
For more information, check out David Ebbo’s blog.