Question on business want for PHP

Hey there, I'm hoping I'm in bounds of the purpose of this news mailing list with this post, but I guess what I am wondering if how much of a demand for PHP programmers is there in the business world? Reason I ask is because I am going to be a freshman college student very well versed in PHP and living in the Chicago land area (actually I'm going to school right outside of the city) and I have been contemplating on what type of a job I'll be able to find when I attend. Is it worth it for me to look for companies which might need PHP based solutions? Also, I don't have any type of certification, is there something I should be looking toward? And finally, I'm assuming most of you guys have portfolios of some sort, what do these look like? I would love to program in PHP and design write applications for businesses, but is this probable/plausible, or am I hoping for something I won't find? Thanks, - Stan