I'm in the middle of upgrading my VPS server from PHP 5.1.6 to PHP 5.2.1. So if you don't hear from me anytime soon...you now have an explanation.
Actually, I'm not too worried about breaking the server. I am however worried about breaking a few of the applications that may not be compatible with PHP 5.2. Also, about half the time I recompile Apache through Cpanel on the server I find I also need to spend some time also restoring eAccelerator. The worry has nothing to do with whether I'm up to the challenge but more of a time issue. I don't know what it is, but everything in my IT world seems to be hitting at once. Anyway, here goes...
Updated: 1:35 PM CDT: So far I haven't seen any conflicts between PHP 5.2.1 and the applications I'm running on the server. I did have to raise the memory_limit in my php.ini and make a new install of eAccelerator. It cost me a little bit of lunch time, but that is about it.
Updated: 316 PM CDT: Wow, all my sites on this server seem to be zipping along. Perhaps the observed performance boost is due only to a reboot of the server, but I'd like to think that it has something to do performance improvements in PHP 5.2.1. One additional change I also did was remove the Microsoft Frontpage Server extensions. I haven't used Frontpage in years.