Adsense allows immediate access to your account once you sign up. Previously you have to wait for your account to be approved before accessing your account.
AdSense allows website publishers earn money by displaying targeted ads next to online content.
To sign up for AdSense
1) Sign up for an AdSense account by enrolling your site at http://www.google.com/adsense/
2) Start adding adsense ad code to your site. (According to Google, it typically takes 48 hours to complete the site review after you add the code to your site. Until you pass this review step, your ad units will remain blank.)
Make sure your website is compliant with the AdSense program policies.