What's up with Gmail?

On the off chance that someone (else) actually reads this... What's up with Google's GMail service?

Here's the deal:

I checked my inbox last week and had 50 invites. I gave away 2.
I had 50 again Monday morning.

I have been talking to a few people, and have heard some very different opinions on what GMail is doing.
Some of these opinions can definitely be classified as Fear and Loathing; to wit, that GMail is actively tracking individual users' mail content and personal information... Not passively tracking via an automated system that serves up the proper ad based on the message content, but an Echelon-like surveillance system.
That is a scary thought.
So... who knows what? Is this the real deal with GMail? Or is this fear, uncertainty and doubt?
Hey, it's a free GB (or so) of storage on an ad sponsored site. I don't have a problem with something crawling through my mail to bring me relevant ads. I do have a problem if someone is creating a marketing profile of me based on what I choose read and what is sent to me.
Again, do you know anything? Someone care to enlighten me while I re-read the TOS for GMail?

Drop me a line, theaxon {at} gmail (dot) com[period/EOL/EOF]