Like YouTube, Picasa and Blogger were Google's acquisitions. The name stayed the same through the years. Now, after the advent of Google+, the company is renaming several of its non-Google brands.
So Picasa is becoming Google Photos. Blogger becomes Google Blogs. However, sources claim that the YouTube brand (thankfully) isn't going anywhere soon.
As you may remember, Google shut down Google Video down in May of 2011. It was a long discontinued service due to YouTube acquisition.