Which browser are you using ? You might just need to refresh it.
What is wrong with the formatting on Chess.com?

It does the same thing in internet explorer (i normally use mozilla firefox). I checked my phone and it does the same thing there too.

Formatting is not fine, text inside the sidebar is centered. Nothing a quick greasemonkey (or tampermonkey if you use Chrome) script won't fix. Or you can fix CSS with Stylish, even easier.

In the column on the right of the screen with messages, group activity, recent forum activity, etc, all of the text is center-aligned. Is anyone else experiencing the same issue?

I have the exact same problem, and it's quite unsettling, really. Just as macer shows, I have the exact same formatting issues: notifications appear centered, same with most recent posts in forums, and I can't even look at the games I have under the "games" tab, nor what people have put in their "about me" sections. Instead I just get a white blank page, like this:
This image shows my game tab. No matter where on the page I look where my games usually would be, there simply is nothing, and it looks exactly the same when looking in the "about me" section.
I have tried this in Firefox (fully updated: version 31.0) and Internet Explorer on my PC, and Safari on my phone, but it looks the same on all of them. I've even logged out, and looked when a friend of mine was logged in, but I was still having the same problems.
Seeing as so many people seem to be having this problem, I wonder if it may be worthwhile to send a ticket to Chess.com so they're notified about this problem as soon as possible.

http://www.chess.com/forum/view/help-support/format4
Something's definetely wrong with the "most recent posts".

It looks like only premium members can view those tabs.
The 'Gay Torrents' bookmark is a bit embarassing.

It would be an extremely disappointing development if that useful info was now only restricted to premium members.

It looks like only premium members can view those tabs.
The 'Gay Torrents' bookmark is a bit embarassing.
Out of everything there, you just HAD to point that out. :p *completely unashamed*

Wow, restricted to premium members? That'd at least be in line with what I heard from some of my friends. They are premium and reported no problems whatsoever in viewing those tabs, probably thinking I'm just absolutely crazy. But if that were the case, then I really think Chess.com are milking the extent of premium exclusivity! Those are some fundamental parts of the website completely crossed out, after all, and it'd just be extremely inconvenient of them to do that, for the players.
Seeing as it happened completely unannounced it's probably just a bug, though, right?
Starting a few hours ago I noticed the formatting on this website is really weird. All the text is displayed wrong and when I go to people's profiles I can't see anything under their about me and games tabs. It's just blank. What is going on here?