James Fuller has posted a review of the online code editing tool Cloud9 and how well it works for his PHP development.

At first I though Cloud9 would be a simple editor, perhaps a nice showcase of what you can do with HTML5 and some well-written javascript but it quickly became evident that this app was packing a lot of powerful features. [...] Sounds pretty awesome if you think about it. You can even connect you own server via SSH instead of using the build in sandbox (this is a paid feature). Is this the Holy-Grail? Not Really, but it’s close. This is a very exciting product that almost reaches holy-grail status, but it falls short in a few key areas.

He includes a little bit about trying to use PHP 5.5 in the Cloud9 editing, and points out that while he was (eventually) able to get the PHP 5.5 alpha compiled, he wasn't able to get things like memcache compiled and working.

The Cloud9 team has done a great job removing the barriers to getting a simple idea out the door. I implemented FizzBuzz in PHP using Composer, PHPUnit, and some SPL interfaces and got it all done , and posted to GitHub in about an hour.