KevinJones... for me there was a bit of a lag between cPanel and FTP working and the site itself coming up. Also the old 404 page is a good sign as it means your site is coming back up. Keep clearing things and if your site is bookmarked, make sure the http is typed in the browser. This was the scenario for me last night.
Interworld, how long of a lag was there for you? It has been an hour and a half, and I still have no HTTP access. I am wondering in case there might be some other issue, but I don't want to jump the gun and open a ticket if it is not necessary.
Again, I don't believe browser caching is an issue here (cleared cache, tried curl)