I have been an entirely PHP guy till now. I learnt JSP out of curiosity too but haven’t used for any substantial project. Not that I think JSP not, its great. But I have used PHP coz I use Drupal. So until now my Server Side Scripting experience was mainly limited to PHP with a sprinkling of JSP.
I did not really bother to learn about ASP.Net. Now because of Imagine Cup, I am having to learn it. And I have to say, its really a great technology. I like its approach towards Server Side Scripting. And yes, I do think PHP developers need to learn a thing or two from the ASP.Net camp.