First of all let me explain who I am: I am a PHP Developer working for a company developing their CMS which handles online stores, data feeds and other content like blogs. I have been programming for 6 years and 4 of those have been in PHP. (I used to be a C# developer).

My question is regarding PHP frameworks. I see so many jobs asking for zend, cakephp and other MVC types of frameworks. However, even as an experienced developer I have never used a PHP framework. Should I start learning? If so where do I even start as there are so many.

I am about to re-write so much of my work's CMS and I'm wondering whether I could help myself a lot by using a framework. What do people think? Considering I will be re-writing a lot of the online store stuff... I am experienced in OO and I have used the .NET framework in the past.

Thanks in advance for the replies.