Same here, since Pinboard is protocol compatible to Del.icio.us its well integrated almost everywhere (also an option in lots of mobile apps). Everywhere else I use just the great boomarklet.
Especially great is their page archiving ... goodbye link rot and you can even download the archives of your bookmarks
One more Pinboard user here. Been using it for half a year and love it for its minimal UI, speed, stability and powerful tagging system. 2200+ bookmarks at the moment.
And count in one more fan of Maciej with his sardonic PR. :)
Same here, since the Great Delicio.us Exodus. The really great thing about pinboard is its twitter integration: if I tweet a link, it gets automatically bookmarked for me with the tag 'twitter'.
Especially great is their page archiving ... goodbye link rot and you can even download the archives of your bookmarks