Some newly introduced PHP features fall flat because there's no guarantee they'll be supported by default in hosting environments.
The biggest peeve of mine is the short_tags setting that enables and tag syntax. I argue PHP should've enabled this feature by default, rather than opt-in.
== EDIT ==
In PHP >= 5.4 the short_tags setting is no longer taken into consideration for the shorthand echo statement , as such it will be available in every hosting environment that supports PHP 5.4 and up.
