If you are planning on playing PTQs, though, it would make sense not to wait for Worlds to be working on your decks. All of a sudden there is a raft of extra information, and there are plenty of new cards that have proven their worth.
Interestingly, Shards of Alara hasn't spawned many new archetypes. Extended doesn't tend to be a format where creating whole new archetypes from nowhere is a sign of a neat and balanced set. Even something that seems quite centered on one block, like Goblins or Dredge, will actually pull heavily on the whole card pool for what is a large format.
What Shards has done is to take some decks from fringe playability and make them strong. When I'm talking about this, my first thought is Elves!. Elves! is a great example of a deck that is a conglomerate of great cards from a variety of sets that finally gets the push it needs to "go pro." One of the big parts of this is Elvish Visionary. While this little two-drop is quite innocuous in many formats, it is a crucial team player for the Elf deck. Wirewood Symbiote can turn it into a card-drawing engine, allowing the deck to hit critical mass of drawing, to keep its engine running. Crucially, Elves also tends to win with Predator Dragon. This hasty devour beastie proves a very straightforward way of converting an elvish throng into sufficient damage to kill right then and there, and is fetchable by Chord of Calling. Various other versions have been seen to run Ad Nauseam, and some are running Tar Fiend or Mycoloth as other dangerous Chord targets in sideboards. At least one player has even chose to go with Sarkhan Vol, contenting himself with attacking with all those Elves right away.
Zoo, with its (at least) four-color mana base, was always going to be able to fit in efficient threats if they were presented, regardless of their color. Wild Nacatl makes Kird Ape and Isamaru, Hound of Konda seem a little small all of a sudden, with Ravnica duals easily making it a 3/3 most of the time. On top of that, there are some nice aggressive disruption options that have proven very popular. Ethersworn Canonist and Tidehollow Sculler are Esper's contribution to Zoo, while Blightning has also seen some play, making life difficult for control players everywhere. Finally, Antoine Ruel's Invitational card, Ranger of Eos, has seen some sideboard play, fetching Wild Nacatls and similar in what feels like it may become commonplace fashion in the weeks and months to come.
The other real aggressor in the format, Affinity, gains Master of Etherium, a potentially massive threat, and has an option on Soul's Fire, to make the most of having such massively powerful creatures. Affinity hasn't performed as well as many pundits had thought it might this weekend, but it is a deck so fast that it would be dangerous to start removing too many sideboard cards against it.
The latest version of Dredge includes the nice little upgrade of Fatestitcher, to serve as a role-player for a whole host of situations, whether it be to tap that last blocker or untap your own Magus of the Bazaar, with the unearth mechanic playing nice with the deck's overall plan.
Perhaps the most interesting new card in Extended from a deck standpoint is Tezzeret the Seeker. Kenny Öberg of Sweden has been tearing up the field this weekend with his mono-blue Tezzeret deck dubbed "The Tezzerator." It leans heavily on the artifact-loving planeswalker, to fetch up key answers to problematic threats on the other side of the board and often to provide a final win condition with his ultimate ability. The majority of the other cards in the deck are a cross section of some of the best artifacts and blue control cards in Extended today.
To cap things off, one new deck that is just beginning to emerge and find its feet is a Bant aggro/control deck in the mould of Haterator, but with Rhox War Monk, Bant Charm and a few counterspells to trade off one for one before finishing with a big Battlegrace Angel. While at first glance the deck could almost be confused for a Standard deck, it proved powerful enough to get a few players into Day Two, and as such might well be worth a second look.
It is likely that between now and Worlds, Extended will solidify a little, with decks changing to reflect a more widely known and understood metagame. One way or another Shards of Alara looks to have made its mark here in Berlin—expect it to do the same in PTQs coming to your area soon.