Eurogamer has word that the beta testing for Mythos shut down on Friday, and while all the intrigue surrounding developer Flagship (story) might suggest otherwise, the post on the Mythos Website optimistically calls this a "hiatus." Here goes:

We, the ancient elders of Uld are issuing this warning to all citizens and travelers. Hurry! The great darkness that once plagued Uld is returning. Everyone is ordered to close down their shops and prepare. We predict the when night is at its peak the darkness will arrive. The ancient elders of Uld will be leaving immediately in order to preserve the lore of this wonderful world. Citizens please prepare thyself and know that the elders will be back from their travels some day.

We regretfully announce that on Friday, July 18, 2008 at 11:59 CST the world of Uld known as Mythos will be going on hiatus. On behalf of all of the Devs and Community team we want to thank you to everyone for their support and assistance with Mythos Alpha and Beta testing and we hope to see you soon.