Is there any conventional SEO wisdom regarding changing the file extensions of ranked pages? That is... having need to update xyz.htm to xyz.php, what should one do to maintain hard won position in the serps? (actually am counting on the updated and now dynamic content of the xyz.php to improve position in serps, but have to get them indexed first?)
What kind of input is that? Don't post unless you actually have somewhat of an intellectual response... Tjmcd - Google will see the two different extensions as seperate pages. Since you don't want to get hit with duplicate penalty charges, I suggest running a 301 redirect from your old .htm pages to the .php. That just tells google that you meant to switch the extensions, and that the .htm pages will no longer be used for the same content.
Thanks PoohBear, Got it. Leaving the old.htm in place I had implemented a javascript re-direct with a nice big div letting the user know they were being redirected, but I could see right away (first Yahoo crawl that is) that this was NOT the way to do it, which then started making me nervous. Quick! Let's fix this before googlebot comes through again or we're screwed! Took a little fiddling to get the 301 right, but it's all good now. Cheers!
sorry, didn't knew this was an "intellectual" forum... lucky me you're here! for me it's STILL a very good question. and also a great answer.
Your answer would be Mod_rewrite module of Apache. Take this site for example: http://www.nationalvisas.com.au/aboutus/aboutus.htm As you can see its file extension is .htm, but it is actually in PHP. We used mod_rewrite to make PHP extension to our desired HTM URL. For more details on the usage check out: http://www.devshed.com/c/a/Apache/Search-Engine-Friendly-URLs-with-mod-rewrite/