didnt SE say somewhere that each character was going to choose their "guardian" spirit or something at the char creation screen? the implication was that these were all summons that had some sort of effect on the character.
maybe im just remembering a dream as a news post, but i swear i read that somewhere. if they did anything, id imagine they wouldnt limit it to a specific class and theyd allow each char to summon their guardian spirit, as a form of 2hr ability. likewise, if they do add a specific summoner class, id imagine they would do as they did in ff12 and bring in a whole new slew of summons, instead of the "OG" summons everyone is used too. if they do that, i hope to fricking god that they include zeromus as one of them. not only was he my zodiac sign in 12, but as the pure embodiment of hate from 4, he has a soft spot in my heart.
They did indicate that each character would select a guardian sign, IIRC, based off of one of the twelve gods of Eorzea. But to the best of my knowledge they haven't said what effect this will have. I highly doubt that they're the equivalent of summons, though. More likely they'll have some sort of passive bonus on stats/abilities. Most of the gods seem to lend themselves to certain stats/abilities...(one is for war/strength, another for building, another for intelligence, etc.)
Here's the Eorzepedia article: http://www.eorzeapedia.com/wiki/en/The_Twelve