I know of a few people who have been holding back from buying Yummy while they wait for Yahoo! to release an official iPhone client. Now a post hidden in their support forums (near the bottom of this thread) makes it very clear that they will not be making one available:
“This has been covered in a few locations, but let me confirm once and for all that there will be NO Delicious iPhone app.”
In my experience — both as a user and as someone who sees a reasonable number of feature requests for Yummy — I’m not convinced that their reasons hold water. Nevertheless, that’s the way things are.
So if you do want a Delicious.com client for your iPhone or iPod touch you’ll need to pick up one of the third-party applications. May I suggest that you consider Yummy.