I haven't used the systems you've mentioned.
However it has always been easier to aggregate useless "garbage", than useful information.
Remember "Web Portals"?
What about Security?
Who cares if someone knows what news feed you are receiving?
I'm sure employers will be overjoyed when their trade secrets are being intercepted/scrutinised, whilst they are being transferred to Dropbox or to an employee's iPad.
Keep Up with TechRepublic