It seems people are scared to take the cubes test. You should be. Preliminary norms suggest the test is VERY VERY VERY hard. Of the readers who have taken the test so far, nine of you reported scores on either the SAT or the Wechsler. SAT scores (reading + math) were converted to IQ (U.S. norms) depending on the time period they were taken. If someone reported scores on both the SAT and the Wechsler, I took the average of both.

I found a 0.48 correlation between raw score on cubes (out of 17) and reported Wechsler/SAT score. After correcting for range restriction, the correlation increased to 0.58. By lining up the cube raw scores from highest to lowest beside the Wechsler/SAT scores from highest to lowest, I found the following rough equivalencies. Do not extrapolate beyond these norms as the relationship is anything but linear (as commenter Fraz predicted).

cubes score (out of 17)IQ equivalent (U.S. norms)
11144
8136
7130
6128
4127
2103