Savant is what you are looking for. Its a nice wrapper class that allows you to use the PHP operators in your templates instead of interpreting an new template language on top of PHP.
Pros:
It makes sense not to add extra work to the system.
No learning curve for developers
If you everyone is disciplined then this is the way to go. (Savant)
Cons:
Although Savant encourages you to separate properly it doesn't force the developer to separate business logic from development code. I have a rule that should never be broken. You can only output variables, use conditions and loops in your templates. You must never allow a developer to create variables in the template. Unfortunately developers never seem to do this no matter how many times you tell them. So, using a engine like Smarty then becomes worth it because the developers are forced to completely keep business and design apart.
If I'm doing a project for myself or one that doesn't have many developers I tend to use Savant. If its a project that is much bigger than just me then in the Architecture I'll go for something like Smarty.
Either way, the separation in the code is important weather you use Savant or Smarty. I'm sure there are other good options out there too.