PHP 4 or PHP 5

[eluser]dtrenz[/eluser]
That makes sense, but PHP5 is backwards-compatible.

So, one day (I assume) CI will be released in PHP5, and all of your code will still be in PHP4. So will you rewrite all your old code in PHP5 so you have a match set? Or will you not install the PHP5 release?

We're not far from PHP6.

Also, PHP5 core comes with some great modules that are going to become essential for Web 2.0 applications (e.g. json_decode/json_encode for one).

There's nothing worse than browsing the PHP online documentation and finding the perfect function for your script, only to discover that it's not available in your install/version of PHP.