Looks good! A couple notes

http://demo.silverstripe.com/general-discussion/ looks a bit rough. A couple things you could try is to use a couple graphics to separate the areas around the forum maybe a background on the search on the right. The currently online heading and the text is a bit big don't you think for such a small feature as that? Its way too big on the default theme but thats a bug If you just reduce it down to 1.1em or around that so it doesn't overshadow the forum threads that would be good

A couple other suggestions would be to remove the padding left on the h2's. It looks a bit weird having 25px of space there. Nudging it in is a good idea but perhaps only 2 or 3 px.

I was on a fresh test local version. I posted that link so people knew what page I meant.

What I was saying the currently online text is too large, and it doesn't need to be so large. and on the forumholder you have alot of information at the top and I suggest maybe it would be nice to break it up a bit. Eg put the login form and links in the box with a different background and a border just to give it some structure eg I did this in Firebug quickly to just show what I mean
Forum.css (line 710)
#RegisterLogin {
background:#eee;
border:2px solid #CCC;
margin-bottom:15px;
margin-top:10px;
padding:6px;
}

That breaks up the large whiteness up there and gives a bit more structure.