Start: Thursday, March 4th at 8:59am Pacific Time (11:59am Eastern Time / 8:59am GMT / 9:59 Central European Time)
Just posting this up in case anyone is interested, this also applies to City of Villains or any combination of the two you might have had in the past. If you ever had an active account (not trial) for either one, this weekend your account is reactivated for free, with all your characters still there (they may have their names changed depending on how long you've been gone).
Not only that, but there's also double experience this weekend as well, and on top of all that, they're also giving everyone free server transfers. If you've been away from the game for a while, a LOT has changed, such as sidekicking/reverse sidekicking working for entire teams now, higher level players gaining xp for reverse sidekicking with lower level players (a 40 playing with a team of 10s will still get xp appropriate for his level range), and level restrictions were taken off of most zones, making a team with pretty much any makeup a possibility.
Other changes include new powersets, the mission architect, weapon and power customization, and new zones/badges. Levels 1-20 are sped up a ton, and there's ways to get jetpacks as early as level 5 to ease the wait until travel powers.
If anyone is interested, the client is here, for PC and for MAC and yes any account will work on either client.