You've probably heard about Google's new social network;
Google Plus. Currently you'll need an invite to join, but soon the doors will open publicly. Of course you can also share your photos via Google Plus, it's easy, but think twice before you upload your photos to Google's services.
When you do submit your photos to their servers they claim the right to use your photo as they please. Well, at least that is what it sounds like when you read their
terms of service (I don't have any legal background). Take a look at this passage:
"By submitting, posting or displaying the content you give Google a perpetual, irrevocable, worldwide, royalty-free, and non-exclusive license to reproduce, adapt, modify, translate, publish, publicly perform, publicly display and distribute any Content which you submit, post or display on or through, the Services.
You agree that this license includes a right for Google to make such Content available to other companies, organizations or individuals with whom Google has relationships for the provision of syndicated services, and to use such Content in connection with the provision of those services.
You understand that Google, in performing the required technical steps to provide the Services to our users, may (a) transmit or distribute your Content over various public networks and in various media; and (b) make such changes to your Content as are necessary to conform and adapt that Content to the technical requirements of connecting networks, devices, services or media. You agree that this license shall permit Google to take these actions."
Google's online services are very useful and easy to use, but before you upload anything it's good to know what you're giving away. These terms also apply to Google's Picasa (soon to be renamed to Google Photos).

Google does make clear you do retain your copyright, but they can use your images to promote services:
"11.1 You retain copyright and any other rights you already hold in Content which you submit, post or display on or through, the Services.
This license is for the sole purpose of enabling Google to display, distribute and promote the Services and may be revoked for certain Services as defined in the Additional Terms of those Services."
Source:
Photofocus