Bullshit. PHP doesn't load everything into its core: it has a well-developed system for managing optional extensions (PEAR).
"Core" extensions are the ones that come with PHP.. This is pretty standard terminology. You just can't be bothered to look it up. Then why reply at all?
For logged-in users, put a 'hide' button next to every mention of a story. When clicked, no more links to the story will be shown.
The quality of the stories appears to have improved sharply. If this continues, I will return to reading Slashdot on a regular basis.
The problem is that organizing stuff and keeping it organized requires a tremendous continuous investment of time on the part of the users no matter how much support you get from software. There is no magic bullet.
Something flat and amorphous at least stands a chance of being used at all. Wikipedia has a couple of post-hoc information structuring projects; I think it's a better approach than overdoing organization before the content is entered.
So if you won't need to merge much, and development is going to be pretty much linear, SVN is OK.
If not, use Git or another distributed VCS.
There is no excuse for using CVS for new projects these days. SVN improves on it in every possible way.
I once tried Debian, intending to switch to it, but I never got beyond the initial installation attempt. The abrasiveness on #debian was my primary reason for giving up and never looking back. (Hint: pick a Debian derivative.)