This would be nice to have added into the next Virtualmin install script. I came across two apps which I used recently which can used mysqli, Drupal & GroupOffice. I was able to make it work on Debian Lenny by using the dotdeb repos, of course had to install Virtualmin GPL the manual way.
Does mysqli conflict with the normal php-mysql packages? (I’m not actually sure I understand what mysqli is…if it’s what I thought it was, Virtualmin wouldn’t really care about it, and wouldn’t need to do anything. But, since I’ve never used it, and have only just looked at the PHP.net doc for it for about 30 seconds, I may just be entirely wrong.)