Its a decent list, but I would have liked to see Kaminari instead of will_paginate and perhaps CarrierWave instead of, or possibly as a really good alternative, to Paperclip.
I've been excited to get this list peer-reviewed and it seems that Kaminari and CarrierWave are 2 good alternatives from all the feedback. I'm looking forward to swapping these in on my next project.
I don't think you will be disappointed with Kaminari, it extends the new query interface really nicely. As for CarrierWave, I find it a lot more flexible than Paperclip.
Also, I hadn't seen Rack SSL Enforcer, thanks for that!
no big surprises, but if you want to know what all the latest apps are running, this is a good list. i rarely start a project without at least half of these.