Since there is a huge discussion flowing on how and when dungeons will be accessable and stuff, here is a small response from the german Com Rep that more or less caused more confusion than clarification. But I wanted to share this nontheless

Original Text:

Ich habe neue Infos, die ich euch zu Mittag als Nachtisch servieren möchte. Es tauchte die Frage auf, ob es eine Art Reservierungssystem für die Instanz-Dungeons geben wird. Nach einigen Diskussionen hat sich das Entwicklungsteam dagegen entschieden. Es wird also heißen "wer zuerst kommt..."
Link: http://forum.square-enix.com/ffxiv/threads/12003-dev1079-Raid-Dungeons-in-Form-von-Instanzen?p=219559&viewfull=1#post219559

Translation:

I've got new information that I want to serve as a desert for your lunch. The question came up, if there is gonna be some kind of "reservation system" for the instanced dungeons. After several discussions the Dev Team decided against one. So it will be "First come..."
I guess everybody can see how this post caused more confusion, since it implies the "dynamis kind of instance" again...

I hate how we can't get simple answers for simple questions-_-