Machinimators have from now until May 18th to enter. However, it looks like a popularity contest, as the community gets to vote for the top 10 finalists, with Cinemax choosing the top three. There are $3,500 USD in prizes being given away, though! For complete rules, check out the official contest page on Machinima.com.
[Thanks to everyone who submitted this!]
If you have machinima or movie suggestions from any MMO, please send them to machinima AT massively DOT com, along with any information you might have about them.