LJ features not in Dreamwidth
Some features LJ has aren't going to be available in Dreamwidth, at least at launch. Some of these will never be put into Dreamwidth while others are just too difficult for now but will be added later. You may also wish to see the changes from LiveJournal page which lists things that have been added or changes, as well as those which have been removed.
S1 Journal Style System
Maintaining and documenting S1 is a lot of work that we would rather put into updating and fixing the newer S2 system. This will never be available on Dreamwidth.
Scrapbook Photo Hosting
This is absent for technical reasons; we hope to eventually add our own photo hosting service with better integration and usability.
This never came out of beta on LiveJournal and has not been used much. If we add something similar it will be re-written with better integration and usability.
We hope to add the phone posting ability some day but would have to re-write it from scratch and negotiate contracts with each country's phone providers which is difficult and expensive.
We're in the same situation with this as phone posts.
This won't be added - we generally think it's better off dead. People who like them can install Snap.com's technology on their browser anyway.
We're not in the business of getting Brad laid. (and, sadly, it never worked for the rest of us)
LiveJournal.app iPhone/iPod Touch Client
Nudge is the work of the devil and has been removed with great glee on the part of our developers.
See also "nudge".