PHP team has released PHP 5.3 RC 2, which will be followed by RC 3 in the next two or three weeks. It means that the final version of PHP 5.3 is getting ready for prime time. As always, changes in 5.x is quite enormous and sometimes makes people confusing because scripts that was working in prevous version become broken on the next version.
For that reason, PHP team has tried to make some documentation on PHP 5.3 Upgrading Notes. Basically, it gives you spesific changes within PHP 5.3 which will give you some hints on what should you do with your scripts related with the changes implemented on the next PHP 5.3. There are some changes that might break your scripts and it's a good time to test for it before it's too late