(December 6, 2014 at 10:09 pm)IATIA Wrote: It is not mandatory and as far as I know, we do not know who has or has not donated.
You are correct that it's not mandatory, nor do I personally think it ever would be.
As far as knowing who has - you can tell, at least those who have donated recently (in the last year or so), their username is displayed in purple, and there is a bronze, silver, or gold little trophy next to their username to indicate what level of support they gave. (In order to get credit, you have to PM Tiberius and let him know the email address you used for the donation, otherwise we have no way of knowing.)
Some have chosen to remain anonymous, including some quite generous donators.