- Is "bookmarks" a problem not yet solved?
- What is the secret sauce of pinboard?
- Is the success of pinboard replicable?
For me, personally, an ideal bookmark solution drills down to just search: Mark a webpage as "noteworthy", enrich it with metadata and offer a powerful search engine limited to these "noteworthy" sites. I use email the same way – no folders or tags, just search.
To OP: Congrats on the Launch! Kudos for optional email in the signup process, open sourcing your work and using Django :-)
Now this is all pretty obvious, but the reason I decided to post it here is I've been using it for nearly a year and even though Pinboard seems much better, bmarks works pretty well for me, so maybe cheapskates like me could find this subset of features good enough too. Also, I really wanted to have a high-density view of my bookmarks (like Chrome/Firefox's explorers).
Regarding the ideal bookmarking solution, I understand the search approach, but IMO tags can be useful if you don't know exactly what you're looking for. For instance, here's  a list of designers/studios I often come back to when I need some inspiration and a a list of lists of films when I need something to watch . You can definitely use metadata to simulate tags though. That's what I do for my music library.
And thanks! I really appreciate it!