The GAO just issued a brief report looking at the services' efforts to mitigate blunt impact trauma by replacing the old suspension system in combat helmets with one that uses padding attached directly to the interior of the helmet.
The report was issued to members of the congressional armed services and appropriations committees to bring their staffs up to speed on how these padding systems came about. It doesn't look at the testing of the systems or anything like that and, to be perfectly honest, it's pretty "no duh" except for a couple things.
First, the report indicates the Army and Marine Corps have been pushing industry to develop more advanced pads that can absorb nearly a quarter more impact than the ones in current helmets. So far industry hasn't been able to meet the requirement.
Also, the services are examining technologies used by NATO countries, including entire padded liners, methods used by high impact sports and even advanced concepts like aqueous liners (a CamelBak on your head?)...I'm partial to the Russian Special Forces helmet myself and I wonder if some of our blacker SOF units are using a similar version (I remember seeing pictures of SF operators wearing modified flight helmets during the overland push into northern Iraq in 2003)...
Take a look at the entire report for some good background on how these padding systems came about and make sure to read page five, which discusses new techs being looked at.GAO Helmet Pad Report