From memory Google also has these types of terms for Google Apps. Google took harsh criticism a few years ago about it but I'm not sure how much has changed.

From my point of view I prefer (but still don't like) Facebooks version because if at any time I feel that my IP is going to be misused I can delete the content or my account and the IP rights I have given Facebook are immediately cancelled and Facebook can no longer use that content.

A few years ago I wrote a custom web application for a print house that dealt with large format file sharing, my lawyers recommended similar terms but instead of this style of disclaimer we found that a liability waiver was better for us and the client. This meant that the sole responsibility for IP rights fell on that of the party uploading the information and we took no responsibility if there was an issue with the IP. The client initially had a problem because of the "what if you screw up and the information gets online before it can be printed resulting in loss of income?", in this case if it was our app that caused the problem our professional liability insurance would cover it but the terms were specifically covering the IP side of the problem.
In response we still supplied the alternative of granting us IP rights and explained that we can act on behalf of an authorised party in delivery if we have a liability disclaimer but without it we would require the IP rights to for delivery otherwise it could be seen as copyright infringement (this is the basic gist anyway).

In our case the issue was 3rd party designers that did not own the rights to trademarks and copyright material were uploading files for printing items such as billboard posters. The designers had the right to provide copies of the material to the printers and companies they use in service delivery (very standard clauses in these types of contracts) so we used that. We also had a box on every upload to the servers confirming that and making it clear that the designer has liability should they be doing something wrong, we also made sure there was a box to confirm that they have permission to provide the copy to our client.

I have been considering redeveloping this over the past couple of months however I haven't been able to get a straight answer if the same terms can be used due to changes in the IP laws. The only thing we have been told is if the client has the server (or VPS) under their name and the software is licensed to allow the upload of items that the client has the permission to provide to the specified 3rd party/parties and the 3rd party/parties are advised of the permission(s) they have been granted prior to download and they must agree then our liability to the IP is almost completely negated with responsibility going back to the user uploading and the licensee that is responsible for the usage of the application being on a server under their control.

But it is a complicated situation, there are a few other aspects but this is the big one.

I hope all that make sense you you guys, I had to re-read the legal liability assessment of this about 3 times before I understood it as this (more basic) version.
What do you guys think of this type of license and solution allowing professionals to securely share their files with clients/colleagues?