What we're really trying to build is the Internet's file system.
As a follow up to my previous post, this is an interesting interview from Dropbox founder, Drew Houston.
I use heavily Dropbox to synchronize contents and share documents between my iDevices and home/corporate laptop and it works without any problem.
I have not used their APIs but I hear it is great. Given the number of apps installed on my iPhone and iPad which uses it to share content, it is likely true.
(via Shawn Blanc)