sometimes I feel as if I've been asleep for a thousand years.
So with zotero. I saw it first in 2007 at Educause in Seattle, thought it was really neat, would make a good end note killer, told a few people about it and then did nothing with it. Mendeley I've never played with. All my interesting, work related pdf's sit on my windows live skydrive in a great chaotic heap. Call me Nennius - but even when I was a researcher and one built collections by writing the details on index cards and organising them I was never particularly diligent. More a pack rat with a good memory rather than organised.
Of course what Zotero and Mendeley do is allow you to build collections, and put metadata around them, ie impose structure. And of course once you've imposed structure you can make your collection available and searchable. Couple this with BibApp and Vitro/Vivo and you've begun to build a social network for e-research which allows people to track down people working in a related field and browse their reference material and share your own.
And of course to do this you need shared storage, which means the cloud. Repositories might reduce the number of items in storage, but will never quite replace the need for some crowd storage as there will always be idiosyncratic material that doesn't quite end up in repositories - pdf's of new scientist review articles.
As for me, I reckon I need to start using these tools properly in order to understand about them, in fact become more structured myself ....