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