While Delicious has not gained a huge number of new features over the last few years, it has acquired a wide range of ways to log in.
A couple of years ago, there was a simple username and password.
Then in late 2009, new accounts came with a Yahoo! ID. Yummy was the first, and for a long time only, iPhone client to support the new accounts.
Even more recently, Yahoo! added the option to create a new Delicious account using your Google or Facebook credentials. I didn’t see an announcement for this. Apparently I wasn’t the only one. It seems that their development team didn’t see the notice either.
That’s right. As I type this, there is no way that I can support Delicious accounts with Google and Facebook credentials. I am told that it’s “on the roadmap” but I’ve seen no indication when we might see that or what it might look like.
In summary, it is not possible for any third-party client, including Yummy, to support Google or Facebook credentials when logging into Delicious. Please do not buy a copy of Yummy if this is a requirement for you.