Free Chatter: all your data are belong to us?

A pun on an Internet meme that I first saw as a hack to World of Warcraft, this is the first thing that crossed my mind when I read the Terms of Service (TOS) of the now free Chatter, released January 31st

First, I briefly used Chatter and it looks like an old version of Yammer. Access via one single email domain, and People, Groups, Files: been there done that. Maybe I should play around a bit more but I'm being a bit careful - after reading this post, you'll understand why

I have a few posts on Chatter, but suffices to say the price per user was aimed at $50 a month before and during development, and lowered to $15 at introduction. A little while later, Chatter became free for existing salesforce.com users, and now it's free for everyone in the world.
Clever move, desperate move, anything in between? I can only guesstimate the motive(s)

A few quotes from the TOS:

"Your Data" means all electronic data or information submitted by You to the Chatter.com Service.

That doesn't leave out anything, agreed? ALL you submit, is referred to by "Your Data"
That is a good and clear definition and sets the boundaries straight, I like that. Now let's see where else we encounter "Your Data" in the TOS. Quite a few places, but let's single out some really important ones:

5.2 Your License to Us. You grant Us a royalty-free, worldwide, transferable, sublicenseable, irrevocable, perpetual license to use or incorporate into Our services any suggestions, enhancement requests, recommendations or other feedback provided by You, including users, relating to the operation of Our services. You also grant to Us a royalty-free, worldwide, transferable, sublicenseable license to use and display Your Data for the purposes of providing the Chatter.com Service, and to transfer such data to Our third party service providers used by Us in providing the Chatter.com Service.

[Italics all mine]

I always have a hard time translating back TOS to "what's in it for me" and "how inclusive or exclusive is it"?
"for the purposes of providing the Chatter.com Service" is a wide definition - does that include marketing and showing samples to others?
Words like royalty-free, worldwide, transferable, sublicenseable license don't make me feel at ease: I'm giving away something for free, and no idea to whom.
There's another interesting one however:

6.3 Your Data. Subject to the limited rights granted by You hereunder, We acquire no right, title or interest from You (or Your licensors) under this Agreement in or to Your Data, including any intellectual property rights therein.

So, that seems to settle that then? What does "Subject to the limited rights" add here? What does "under this Agreement" mean? Is that limiting, or not? Does Salesforce.com acquire right or intellectual property somehow else? Looks like it doesn't, but I am not sure.
There must be an easier way to comfort people reading the Chatter TOS. Yammer TOS make for much better reading:

Some areas of the Service may allow Users to post feedback, comments, questions, data, and other information (“User Content”)
(...)
Except for your User Content, the Service and its materials, including, without limitation, software, images, text, graphics, illustrations, logos, patents, trademarks, service marks, copyrights, photographs, audio, videos and music (the "Yammer Content"), and all Intellectual Property Rights related thereto, are the exclusive property of Yammer and its licensors

Free Chatter. Pulls the security pin right out of your entire company?