There are some small drawbacks on this scenario.
First of all, the problem with the password: If you have one password for all, all have the same username and email address in the background DB. So nobody will be able to have a forgotten pasword to be sent to their own email address. Also, users would be able to change that password through normal procedures and then disable access for all others. Third, you wont be able to track user statistics.
One major drawback is that you would never be able to kick out one user (someone leaves the company or usergroup you share the info to).
Also, if you have the users share the username & password, you will have to have (from the reasons named above) a very easy username and password. So this is a security matter, and so why use a password at all?
In this case I would rather publish the whole page on a somehow "Hidden" URL (domain.com/234234234/ instead of domain.com/)and hence block it from sight. Or simply use a HTACCESS username/password, which would remove all trouble mentioned above. You would simple block access to the whole GL directory with one single username/pw, and make all content in geeklog public. People would then simply be there as guest.
Still, there is no technical issue with your way to do it. Since the Guest user is also a normal user in the database (User 1), and since there are many people who "login" as guest at the same time, there should be no problem from my point of view.
Another drawback of your solution is there in case you ever want to enable comments or else. Then, you would have to ake people again login with a new username and password. You are always in a legal dilemma if anonymous people post comments or else that is followed up by legal action. You better know who wrote what on your page.
HTH
Oliver