So I ordered some mac pigment samples from thebodyneeds.com and Entremauve was one of them. It's a dark purple with some blue and pink reflects. I tried it out and I absolutely loved the results. Since I only ordered a sample I was a bit scared to use it on a regular basis because I didn't want to run out especially since hunting it down is a bit difficult since it's one of those long ago limited edition products. So I was browsing through mac pigment swatches on Specktra and user did a comparison on Entremauve vs. Grape and it's pretty similar. The first photo (above) doesn't really show a strong similarity but I believe its the lighting because the Grape pigment is closer to the light source which makes it appear lighter.
^^ As you can see Grape (regular line) is pretty similar to Entremauve but with better pigmentation.
Hope this helps:)