How does this color blending trick that works on color components in parallel work?

I saw this Java code that does a perfect 50% blend between two RGB888 colors extremely efficiently:

public static int blendRGB(int a, int b) {
    return (a + b - ((a ^ b) & 0x00010101)) >> 1;
}

That's apparently equivalent to extracting and averaging the channels individually. Something like this:

public static int blendRGB_(int a, int b) {
    int aR = a >> 16;
    int bR = b >> 16;
    int aG = (a >> 8) & 0xFF;
    int bG = (b >> 8) & 0xFF;
    int aB = a & 0xFF;
    int bB = b & 0xFF;
    int cR = (aR + bR) >> 1;
    int cG = (aG + bG) >> 1;
    int cB = (aB + bB) >> 1;
    return (cR << 16) | (cG << 8) | cB;
}

But the first way is much more efficient. My questions are: How does this magic work? What else can I do with it? And are there more tricks similar to this?