NOTE: Block has changed significantly since this article. I will attempt to write up a better description at some point, but in the meantime, consider this historical only.
This is what Google says that Block does:
1. You will no longer see this person's content in your stream.
2. This person won't be able to comment on your content.
3. This person will be removed from your circles.
4. This person will still be able to see your public posts.
This is what Block actually does.
1. You will no longer see this person's content in your stream, however you will still see their comments in the Notification pull down, you will see their comments if you go an actual post page, and you will see all their public content if you view their public page.
2. The person will not be able to add any new
comments to your posts. However they can continue to edit old comments, and they can still share your posts. They can not, however, + mention you in any posts.
3. This person will be removed from your circles (and put in a "blocked" circle). However, you will not
necessarily be removed from their circles. When I checked, it still had the account in the circle, it was just now only an email address, not a link to a profile. This is probably because I already had them in my address book, but I'm not certain.
4. This person will still be able to see your public posts if
they go to the link to a post, or view your profile page. They will also
be able to see your comments in their stream (even though you don't see theirs) on posts (public or limited) which you are both able to see.
Because blocking is really only an operation on your stream, it also does not block them from seeing who your friends and followers are, or who your common friends are.In summary:
Blocking people hides their posts and comments from your stream, and hides your public posts, but not
your comments from their stream. It does not hide either posts or
comments when viewed directly on a profile or in the posts themselves.
It actually does more to hide them
, than it does to hide you from them.Block does not block. It's a mute button, useful for muting over-sharers.
A proper block botton would do the following.
1. Remove me from their circles.
2. Not allow them to see anything about me (posts, comments or
profile information) while they are logged in.
3. Remove them from my circles and add them to my "blocked" circle.
4. Probably, to be fair, also not allow me to see anything about them anywhere on the system while I am logged in.
In short. While using the system, we should be invisible to each other.
As +Gretchen S.
has said, "Google+ is different from Facebook in how much of the important discussion, such as this one, take place in public. That's an important difference, but it needs to be matched by a greater ability for privacy."
Mute is a useful function, but let's call it what it is, and let's have a real "block" so that people can use Google+ with the knowledge that anyone who is stalking them needs to actually leave the system in order to track down what they've been saying.
--- Added after posting ---
I do have mixed feelings about the fact that truly blocking someone doesn't really keep them away. But actually, there are some additional layers of security that could be applied.
1. Let me specify that my posts are visible only to other Google+ users. Then they wouldn't show up in a public Google search, and they wouldn't be visible if you were logged out. My stalker would have to create a new account to view my profile.
2. Take that one step further, and (assuming Google implements internal search) not allow that to search my "public" posts either.
None of these truly protect you from a dedicated stalker, but security has never been about "you are secure" versus "you aren't secure". It's a question of what degree of safety you want and what level of pain your willing to put up with to get it. By providing additional options, even the "you can only see it if you log out", you are giving more opportunities to pick the level of security that they require, and making it possible for more people to use the service without having to curtail their activities. In the end, it is not up to pontificators who say "but that's not truly secure" to make the decision, any more than you let someone else tell you how much life insurance to buy. It's a choice the individual has to make based on their circumstances. Google serves us all by presenting a range of options and letting people pick the best fit.
P.S. I also have sympathy for Google from a technical standpoint. Allowing post pages to be filtered is going to blow what is right now probably a static cached file. Oh well.