I highly doubt it's a shock absorber because any give in the structure would cause the glass to bend or warp which in turn would cause it to shatter.
These are definitely shock dampers.... I respectfully disagree with your statement. Looking at the connectors that fasten the screen to the metal ring chassis (Gizmodo pics), the screen should "float", meaning, the screen (and maybe the back....haven't seen pics of it clearly enough) is allowed to travel ever so slightly parallel and perpendicular to the plane of the screen, fairly independent of the chassis. So if the chassis deforms due to an impact, the force of the impact will be transferred
around chassis to the "rubber" seams, where the shock is dissipated enough to protect the screen and, presumably, the back of the phone. I would bet that the phone could take a fairly significant impact... maybe a 6 foot (~2 m) fall. Hard to say, though, without knowing exactly what that material is.
In other words, the seams are just shock dampers. Ask any engineer...they should agree with my analysis.