Single Sign On is a mechanism that creates the feeling of a single ecosystem across multiple services for a user by sharing key elements of an identity. SSO can provide users with a better experience and can result in cost savings. This article looks at how Intuit implements OpenID 2.0 as their SSO.
Back in the good old days things were a lot simpler. You didn’t have to worry about packet capturing or password extracting, and as a result a lot of the original protocols like HTTP, FTP and POP3 didn’t worry about sending your passwords over the wire in plain text. But in today's increasingly sophisticated API-driven world this isn't enough.
Additional third party integration with Gmail has been possible (you only have to look at all the contact import features from sites like Facebook), but these have either been clunky manual procedures that involve exporting contacts to a CVS file, or they require you to supply your email password. Neither option is all that attractive. Now there is an alternative. Google have recently added the ability to access the IMAP/SMTP features of particular Gmail account using OAuth.