Okay, Listed here are three Facebook Web addresses:

http://facebook.com/about [A Facebook Page]
http://facebook.com/zuck [Zuckerberg's Profile]
http://facebook.com/like [About Facebook Like Button]

Basically have two pages:

http://example.com/user.php?u=[username]
http://example.com/page.php?p=[pagename]

I've effectively rewritten the consumer.perl as http://example.com/[username] but next after i make use of the same code for page, and then try to access a webpage like http://example.com/[pagename], a userpage (404 page, because no user with this title is available but a webpage does) seems. So, What must i do in order to remove this conflict.

NOTE: I'd rather not use Web addresses like http://example.com/user/Username and http://example.com/page/PageName. Help.

You have to rewrite all web addresses to some separate php file that picks up if the parameter is really a username, or page title. The php need to look something similar to this:

$name = $_GET['name']
if( userNameExists($name) )
  include('user.php');
else if ( pageNameExists($name) )
  include('page.php');
else
  include('404page.php');

You have to implement userNameExists() and pageNameExists() off beam.