So, I just went onto PES, and I got a warning message saying, "WARNING! Your browser does not recognize the certificate of this site as belonging to 'login.gamespy.com' Someone may be trying to intercept your browsing session"

Now, I have been on PES with this (my) browser before, and I have not encountered any problems.

So, I am wondering, is the site getting hacked, or does it just have a new certificate?

That sounds like a redirect, although I could be wrong. Advertisements on PES do this alot. Ever seen those annoying advertisements that say "click here to continue on to PES?"

And if it makes you more comfortable, it's always a good idea to have a program such as SpyBot or Ad-Aware do a scan every now and then.