Nessa has a new post to her blog today on why she thinks most people are late to the party on PHP 5.3 including a few reasons she sees for the delayed adoption among the developer masses.

As a programmer, I would hold it to any site owner to check their site’s requirements and the offerings of their host before they unnecessarily waste a lot of time and money, but as a system administrator I frown upon shared hosting providers offering software with known compatibility issues just to be able to advertise as the “latest and greatest”. The latest isn’t always the greatest, and it won’t be until the community catches up with what the greatest has to offer.

She notes that her situation, much like many other hosting companies, is that they're "just not ready" to make the upgrade because of some of the hassle it might cause the users. Similar situations happened with the change from PHP4 to PHP5. She also mentions a few specific issues:

• Compatibility issues - several very popular applications don't support some of the 5.3 changes
• There no Zend Optimizer/Zend Guard support
• It's not required for PCI compliance yet