Can't install 1.22 Google Drive version on OS X Yosemite 10.10.3
Well, I have found a "solution". First, I guess my problem is that I am among the new testers of the new version of Google Drive.
The solution I have found is brute-force : I copied the application straight from my macbook to my imac, rebooted and I finally able to sync files between my local google drive and the online folder.

It works, but this is not such a clean solution. When you click on the button "download Google drive" from the web interface, the installer script is supposed to determine which version you shall download, and that doesn't take early-adopters into consideration. Hopefully they will soon address this issue.