This is very misleading. The headline reads as if GNOME has not had any drag-and-drop support until now, which is ridiculous. The Digg headline was even worse: "GNOME Gets Real Drag n' Drop Support with XDS". Bullshit.
What actually happened is that Nautilus (the GNOME file manager) has received a patch to support this extension in the main window bit. It will probably help File Roller act more intuitively with respect to dragging files to Nautilus windows, and it is a good thing. It won't work with Nautilus's list view, yet. It is also possibly the least interesting of the new features in GNOME 2.20. It deserved one sentence tagged on to the File Roller bit of the release notes. I am not going to "scream with joy".
Incidentally, GNOME 2.20 is a fantastic release, and has caught me by surprise. EOG (the image viewer) has been almost completely rewritten. Evolution now has several small new features that I've been wanting - new mail notifications, and warnings about missing attachments. There's some nice GNOME Keyring integration going on... even the default theme looks shinier. So, there are plenty of other, better features to say "finally" about.