If you call the poll answers 0 for "not online" and 1 for "online", standard error can be calculated easily. First, standard deviation = square root of [mean of squares - square of mean]; both 0 and 1 are identities under squaring, so the mean of the squares is the same as the mean. So, stddev = sqrt(0.67 - 0.67^2) = 0.470. Standard error is calculated by dividing this by the square root of the number of samples; 0.470/sqrt(6403) = 0.00588.

That's an error of +-0.59% for both percentages, making the difference between 66% and 68% even less significant. The fact that only two digits of them are presented adds another +-0.5% error for both values, in a flat distribution. I don't know how to calculate the resultant significance, but it's pretty damned negligible.

If I've made an error, someone please correct me.

An expansion is on its way, it's official. Nothing else is known about it though. There's some rumours on http://forums-en.wow-europe.com/thread.aspx?fn=wow -general-en&t=481612