It is a great new feature, because I can finally keep my data in the same place as the workflows and control both of them from the same platform.
Install the new KNIME. In the KNIME Explorer create a new workflow group (I named it "data"). Now, drag and drop any file from your file system into this workflow group and you should see it appear in it.
The File Reader node uses now the "knime:" protocol and not an absolute path, making the node and the workflow much more portable across workspaces and machines.