"big Brother is watching' is fine and dandy if it is considered necessary for national security....9/11 and similar excuses, but having a Commercial Entity snooping to target you for advertising is repulsive at best.
No-one appears to be bemused by the 'pyramid sales' methodology of promoting Gmail....the 'freebie' advocated by your 'mates' is worse than the spruiking of the Time Share marketeers.
If something 'appears' too good to be true it usually is.
This time, you are required to consent to a private individual's access to your 'private' communications for THEIR Commercial gain, not yours.
Once the 'foot is in the door' you will have a hard time arguing your legal right to privacy in other walks of life......the Lawyer's argument will go ...'you clearly are not 'that' concerned with data privacy as you have consented to its waiving with respect to Gmail, so it flows naturally to any other email accounts as well as they contain equivalent information and telecommunication privacy is already compromised through consent and 'required access' that no 'real' privacy SHOULD be expected.'
There is no difference to having your snail mail opened by 'Posties R Us.Org' and having a Flyer for Joe's Bar and Grill and Knocking Shop inserted because you mention in your letter you like Pizza and sex.
The concept of 'robot reading, not human reading' is laughable.
It is the Legal act of having it READ by a third party that dissolves your rights to subsequent controls.
Spying is a reality of life....long before 9/11....that is just a convenient excuse.  It can be mostly ignored as it is YOUR accepted Government of your own society and existence that is the prime source.....the price you pay for involvement /inclusion within your society.
I am not part of the Google monopoly/behemoth so I benefit not by the profiteering of the targetted advertising but only the sweetener given to the gullible....the chance to have some huge online storage...a GIG, whatever....the very same 'GIG' that they can peruse at their leisure and determine how to bombard you and your friends to whom you communicate with yet more barbed, specific advertising.
Join if you must....it's your individuality and person that is being violated.
Just do not expect everyone on the planet to even want to communicate with a compromised source and end up also feeding the Commercial coffers of Google.
If it wasn't such a clandestine attempt to invade and usurp your rights as an individual there would be no need to adopt the hysteria of peer distribution of accounts.  People would just say 'wow...great idea' and sign up individually.
Top marks to Google though.....inventing a whole new way of separating fools from their money through advertising.
Bloody brilliant.....