Fatal error: Class 'HttpRequest' not found in /var/www/index.php on line 2

he installation guideline is very insufficient. I've installed for Debian lenny/sid with the following step;

apt-get install php5-dev (to enable pecl command)
apt-get install libcurl3 (to get curl support)
apt-get install libmagic

and

pecl install pecl_http

pecl will download and compile but before that just follow the prompt. If the respective development library is not available in your system, the compilation will abort.

You should add "extension=http.so" to php.ini