i've installed (as root)
aptitude install curl php5-curl libcurl3 libcurl3-dev
and added extension=curl.so to my php.ini (i assumed this wasn't done automatically because i'm using Lighty and not apache)
service lighttpd restart
But still no luck, there is nothing about cURL when I run phpinfo()
curl.so is located in /usr/lib/php5/20090626
Try to restart lighttpd by
sudo /etc/init.d/lighttpd restart