This is the best news I've heard in quite some time! I had actually half considered trying to overhaul Links SQL to play friendly with PHP, since the all-Perl approach has limited several things I've wanted to do with my site, but I didn't envy that undertaking.

For an existing site that has hundreds, if not thousands, of category directories/pages (static) indexed in a multitude of search engines, I would think it would be very important to be able to operate the PHP frontend as separate index.php pages to be built through the category.html template in each directory, as well as a single one-in-all page as discussed elsewhere in this thread.

Similarly, if taking that approach (separate index.php pages in each Links-built directory), and if there isn't already such a feature in the latest versions that I haven't yet worked with, a very useful tool would be the ability to un-build the existing index page in each directory at the same time as the new PHP version is being built. Otherwise, you would have to delete them one by one or delete all the top level categories in one fell swoop and hope that you don't have any interruptions rebuilding before someone tries visiting... There are probably some recursive command line tools that could accomplish the goal, but I don't work enough with that to know exactly what they would be.

Dan