Yes LiquidMetal is a family of alloys with cooling properties that allow them to cool slowly in an amorphous form instead of crystalline, so color isn't always the same, it depends on the composition of the alloy chosen for a product.
Like someone said, the way MB Pros are build today has to be costly. Machining from a block of aluminum to almost the finite product is kind of mad with the amount of computers produced every year.
The question is, would the fabrication of the first part trough LiquidMetal injection (which could directly contains most of the keyboard holes and such but still need machining for the small details) be more cost efficient than the current process knowing that aluminum (the raw material) is pretty cheap.
If the switch from aluminum to Liquid Metalalloys occurs it would mainly be to lower production cost, the only benefits the end user could see, would be cheaper computer (knowing Apple I wouldn't hold my breath) or lighter computers (since the process is supposed to offer better mechanical properties, you could reduce the structure size).
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