Adsense will allow users from now on to merge their Google account with the current Adsense login, so that users could use just one set of ID and password. Previously you were provided with separate id password combo for Adsense login. From now on if you are logged in to any other Google services like Gmail or Blogger you can easily login to your Adsense account too.
If you go to the Adsense login page, after login you will be asked if you would like to merge your Adsense and Google account together. If you don’t have a Google account you have the option to create one. Here is the screen shot of the merging request page -
The merging although now optional is going to be mandatory after some time.
Merging compulsory? I didnt get the logic behind this, see if a person does not have a Google account how come he can merge? And if he were to create a new account for merge, then adsense account itself is a Google account.