Sets released: Conflux, Alara Reborn, Magic 2010, Zendikar

Major stuff:

   - Magic 2010 came with a complete overhaul to the rules and the rulebook.
     The important changes are:
     - The base set is no longer purely reprints; it has its own cards
       specifically designed for it;
     - mana burn was removed from the game, and mana pools empty at the end
       of steps as well as phases;
     - the removed-from-the-game zone is now the exile zone, to which cards
       may be exiled.  Cards that fetch cards from outside the game now
       can't reach the exile zone;
     - the in-play zone is now the battlefield;
     - spells are once again cast rather than played, and abilities are
       activated;
     - combat damage is assigned and then dealt in the combat damage step
       without any player gaining priority;
     - when assigning multiple attackers to a blocker or multiple blockers
       to an attacker, the player splitting the damage needs to announce an
       order in which damage is assigned.  When the assignment occurs, a
       later creature in the order can only be assigned damage if all of
       the earlier creatures have a lethal damage assignment;
     - the lifelink and deathtouch abilities became static abilities;
     - the rules on token ownership changed so that the owner is the
       initial controller, to match with more intuitive expectations;
     - the layering rules changed so that:
       - color-changing happens before adding or removing abilities;
       - all effects that set power/toughness are applied before all
         effects that adjust power/toughness up/down;
     - the "bands with other ..." rules were changed so that only one
       of the creatures in an attacking band needs the "bands with other 
..."
       ability, as long as everything else is a "...";
     - phasing changed so that "phased out" is a status rather than a
       zone, and causes the phased out permanent to be ignored except for
       specifically mentioning phased-out permanents;
     - the rules for mulligans changed so that both players decide on
       mulligans simultaneously and then take them simultaneously, until
       no player needs a mulligan.
   - Rules were codified to explain how to use cards like the Planechase
     planes to play Planar Magic.  The Command Zone was added to explain
     where these cards sit.

Minor stuff:

   - Conflux brings back the domain mechanic from Invasion and introduces
     basic landcycling.
   - Alara Reborn contains the cascade mechanic and adds a few multicolor
     hybrid cards.
   - Zendikar introduces intimidate (a generalised fear ability) and
     landfall (caring about lands entering the battlefield).