In the following recent articles, the aether has mass.

'From Analogue Models to Gravitating Vacuum'

http://arxiv.org/pdf/1111.1155"The aether of the 21-st century is the quantum vacuum, which is a new form of matter. This is the real substance"

'Scalars, Vectors and Tensors from Metric-Affine Gravity'

http://arxiv.org/pdf/1110.5168"the model obtained here gets closer to the aether theory of [16], which is shown therein to be an alternative to the cold dark matter."

'Vainshtein mechanism in Gauss-Bonnet gravity and Galileon aether'

http://arxiv.org/pdf/1107.1892"the perturbations of the scalar field do not propagate in the Minkowski space-time but rather in some form of ”aether” because of the presence of the background field"

'Quantum aether and an invariant Planck scale'

http://arxiv.org/abs/1110.3753"this version of aether may have some bearing on the abundance of Dark Matter and Dark Energy in our universe."

"mass of the aether"

'Unified model for dark matter and quintessence'

http://arxiv.org/pdf/physics/0610135"Superfluid dark matter is reminiscent of the aether and modeling the universe using superfluid aether is compatible."

'The aether-modified gravity and the G ̈del metric'

http://arxiv.org/pdf/1109.5654v2"As for the pressure, it is equal to p = 53−αg,6a2 so, it is positive if αg < 3 which is the weaker condition than the previous one. One notes that the results corresponding to the usual gravity are easily recovered. Also, it is easy to see that the interval αg < 15 corresponds to the usual matter."

'Phenomenology of Gravitational Aether as a solution to the Old Cosmological Constant Problem'

http://arxiv.org/abs/1106.3955"One proposal to address this puzzle at the semi-classical level is to decouple quantum vacuum from space-time geometry via a modification of gravity that includes an incompressible fluid, known as Gravitational Aether."