Path of the Titans is gone
The whole Path of the Titans idea has been removed from the game. It will no longer rely on Archeology or on any kind of PvE/PvP progression and instead Blizzard will just introduce a new type of glyphs: Medium Glyphs.
Medium Glyphs will add a "fun factor" to abilities, and it wouldn't be surprising to see something similar to the Fortification or Breakthrough glyphs first previewed during Blizzcon 2009. (But probably not these exact glyphs, a lot of stuff happened since last year)
Guild Talents are gone
The guild talents are gone and your guild now gets extra bonuses depending on its level. There are 25 levels and each level will automatically reward with more cool stuff. The leveling process remains unchanged and your guild will gain experience through PvP, Dungeon and Raid progression, questing, etc ...
Guild currency has also been removed and rewards will just be "unlocked" after you reach a specific level or complete a guild achievement. Once a reward is unlocked, members will be able to purchase it with gold. Some of the rewards include guild tabards, mounts, heirlooms, and it looks like you will finally be able to have a guild tabard on your mount. (Just like the Argent Tournament banners)
New members of a guild won't be able to buy everything directly, they will have to contribute to the progression of the guild before they can access the top rewards. Each time a player helps towards the leveling he will gain reputation with the guild, the best rewards will require players to be exalted with their guild before they can buy it.
Archeology will be less important
With the Path of the Titans gone, Archeology will become a "true" secondary profession and you won't really have to level it anymore. However it will still be used to let you get cosmetic/optional items, get more information on the game's lore, and ultimately it looks like we can expect rewards similar to fishing. (Nothing mandatory, but you'll be happy when you actually find something)
Information gathered from other sites:[list][*]You will find two types of items: Common Artifacts will give you more information on the lore of a race, and might be used in some kind of collection game. Rare items will give you usable items, most of them will be cosmetic but some of them will have actual effects. (Details on Wowhead)