|No such thing as a small change|
First I would suggest not concerning yourself with search engine placement. It is my opinion that this is a antiquated mentality left over from the dot com boom when everyone thought the world wide web would solve all of their company's marketing problems. It doesn't! "if you build it..." does not mean they will come. Companies need to understand that simply having a website will not make people want to visit it and they need a supplementary marketing plan to drive traffic to their site. Tools dont make money, using them to work more efficiently does, and you are building a tool for them. Unfortunately this is rarely understood by those in charge and so aside from a press release concerning the 'launch date' of the new site most of the marketing falls on the developer and his perceived ability to shoot sites to the top of any search at will. Do yourself a favor and concentrate your efforts on making a robust, scalable and user friendly application, because if they want people to come back to the site it needs to work.
Not that I have any strong feelings on the subject...
That being said, the extension on your files will not discourage nor encourage a search engine from listing your site. A quick search of Google on most anything turns up URL's that point to .php, .pl, .asp, .pdf along with html files. I have read somewhere that the ranking and placement within search results, at least for google, is based on how many other sites refer to yours, a sort of XP system for web pages if you will. Many sites also allow you to submit your site for inclusion in their database. If the client is still worried throw some meta-tags on your pages to make them happy and tell them to leave you alone.
Now Perl vs. PHP for your project?
My answer is use the one that you are most comfortable with since it sounds like you are writting a simple content manager. If however you or your client envision extensive expansion of this application into other protocols aside from HTTP you might want to develop it in Perl from the start. Perl is better suited for system type tasks and has been expanded to include CGI & Web related stuff, where PHP was developed with CGI & Web stuff in mind and has been extended into other areas (I think the name came from 'Personal Home Page' early on and has been redefined as 'Hypertext Pre-Processor' though Im not sure how they get PHP from that).
In reply to Re: Are Perl-based CGI scripts seen by search engines?