So I ran "sudo pecl install xdebug" like a good linux user, but was stymied when it threw the error "phpize not found", especially when "sudo apt-get install phpize" yielded no friuts (darn it, that usually works!)

The magic package actually happens to be "php5-dev", so a quick "sudo apt-get install php5-dev" fixes everything!

Now wasn't that simple...of course it made me waste a half hour searching, but, never again ;)