Any time any one person in any organization is a "gate keeper" of any part of a frequent activity, that person creates a bottle-neck. The failure to delegate cripples an organization from being as productive as it could be otherwise. The mark of an excellent leader is someone who delegates both responsibility and authority.
I don't think this is out of the ordinary. Our principal was burned by a "bull in a china shop" leader a few years ago so now she has every flyer run by her. What we do is use Google: we share a calendar so everyone on the board knows when meetings, events, scheduled communications are and google docs to collaborate on files. I highly recommend this system. Saves time on phone calls, emails etc.
We went thru the same thing but then just adjusted our process. Our principal has agreed to get back to us within one week. In the meantime she has given us the green light for putting up brief reminder announcements on our website. We are going to broach the topic of a Facebook page this week with our principal. Wish us luck!
We actually have our principal init. the flier so we know she has looked it over and approves-- sometimes she catches type-o's that 3 of us didn't and if there is a problem with what was sent out-- we had her approval - so she backs us up-- it is a hassle sometimes- espeically because, as we all know, principals have plenty of meetings, get very busy and sometimes it takes a few days to get a flier back- so now we plan ahead--
Our problem is ANYTHING we want to do as a group from the day we have a meeting to the way we elect officers has to be okay'd by the principal. It is so annoying because she is so busy sometimes we must wait weeks to get an answer.
Have you asked the principal if she would mind if you sent out quick reminder emails to your group mailing list without having to run it by her first? I'm sure it's time consuming for her to review everything you send out, and it sounds as if you've had enough of an experience with her at this point, that she should know that you're not going to send out anything crazy. You might be able to come to an agreement that anything with *news* in it will go through her, but reminders could come straight from you.
You could also broach the idea that a PTO Facebook group or Twitter is not "official" school publication, so you should be able to post what you want. Our school's FB group has discussions going on and is a place that anyone in the group can post questions or comments. It's more of a forum than a bulletin board.