A study in the latest Lancet from clinicians out of University College Hospital Medical School, London, is reporting very encouraging results in safety and efficacy of a portable, wearable dialysis system from LA-based Xcorporeal, Inc. 
Dubbed a Wearable Artificial Kidney (WAK), the battery-powered device weighs less than 5 lbs, and is based on a hollow fiber dialyzer with a surface area of 0.2 sqm. The company seems to be hush-hush about the details of its technology. ABC News has a photo of the device.
To learn more about the promises of this technology, check out the reference papers published by the company: Continuous Renal Replacement Therapy for End-Stage Renal Disease (.pdf)…; Continuous Renal Replacement Therapy for Congestive Heart Failure: The Wearable Continuous Ultrafiltration System (.pdf)…
Lancet abstract: A wearable haemodialysis device for patients with end-stage renal failure: a pilot study …
Xcorporeal, Inc. …
Wearable Artificial Kidney (WAK)
December 17th, 2007 
Medgadget Editors Medicine