I had read the original news article about this, and then I must confess I promptly forgot it. The idea was that players were to vote for a Tier VII tank or tank destroyer, or a tier V SPG, and all the vehicles in the line of that chosen vehicle would be the beneficiaries. The offer was 50% discount on the Tier II-V vehicles and a 30% discount on the Tier VI and VII vehicles, and a 50% crew experience bonus on all the tanks in the chosen line. Then there was a big poll put up on the EU forum, and people voted. I did vote, but I cannot in all honesty remember which tank I voted for.
However, today it has been announced that the winner of the vote is the T29, the American Tier VII Heavy. This means that the T2 Medium, M2 Medium, M3 Lee, and T1 Heavy will have a 50% discount, and the M6 and T29 will have the 30% discount. The length of the offer runs from Monday morning for a week.
However also today the EU Community team chose another tank line (essentially through pulling a number out of a box) and for the week from the 27th May the line of the T-34-1 will benefit. Presumably this means the VAE Type B, Type 2597 Chi-Ha, M5A1 Stuart, Type T-34 will get the 50% discount, and the Type 58 and Type T-34-1 will be at a 30% discount.
Personally I am not overly concerned about the Chinese line, but this coming week I will definitely see about getting some games in on my recently acquired M6.