Generally people do one of two things.
A. Using htaccess, set up a RewriteRule for each individual script.
For example, you would set up a rule for pages/8 to pages.php?c=8, a rule for news/2010/03 to news.php?year=2010&month=03, etc.
B. Using two RewriteCond's and a RewriteRule, set it up so that any non-existing files and folders are passed to a single script (known as a front-controller). The front-controller (a php script) parses the URI and determines which script needs to be loaded.