[michaelt]

  Certainly it would be easier, but even NSA
  doesn't have enough hard drives to store
  all of GMail, Outlook.com, Skype, etc.

Gmail has enough drives - why shouldn't the NSA?

Gmail offers 15 gigabytes of storage space, almost certainly over-allocated - I know only one or two people who have hit that limit, personally I'm at less than 3 gigabytes. Gmail has 425 million users, according to [1]

According to Wikipedia's Utah Data Center article[2], it's estimated to have 3 to 12 exabytes of storage in the near term. So, space enough to store 1.0 billion to 4.2 billion 3 gigabyte gmail accounts, or 7.6 to 30.3 gigabytes per gmail user.

Somewhat short of 'all internet traffic all the time' but they could get all of gmail easily.

[1] https://en.wikipedia.org/wiki/Gmail [2] https://en.wikipedia.org/wiki/Utah_Data_Center