Calibrating 27in iMac with Spyder 2, yellow tone.

I would encourage you to contact Colorvision, the makers of the Spyder calibrator, to try to resolve this issue.

You may need new software/hardware to properly calibrate the new LED monitor.

It has a wider gamut and needs different filters in the sensor unit to properly work.

Also, consider lowering the luminance of the monitor as it is too bright at default for digital imaging work.

I can tell you for sure that the software that comes with spyder2 is the worst you can use in terms of color accuracy.
The calibrator itself had no problems with my 21.5'' (which uses the same panel technology and backlight) and produced absolutely fine profiles with spot-on print to screen match.
The thing is that you have to use OTHER software to lead the calibrator like ColorEyes Display or basICCal (I use the 1st). Consider downloading a demo to try before you spend your money on another sensor.

Your settings are pretty much the standard, except the brightness which should turned down to a level that produces screen-to-print match (if that is what you want).

I use the Eyeone Display2 on my iMac and it works fine.

The eyeone will allow you measure your screen brightness and calibrate to that. the recommended brightness for an LCD is 120 which is below halfway on my mac ( 7 marks up from the left)

It will also measure your ambient light, I use daylight bulbs in the computer room so that's OK.

I found the default imac profile to be very close, and would think only need colour calibration if you need accuracy for professional purposes.

Did you resolve this issue? I just purchased and installed Spyder3Pro to assist with color accuracy for photo printing. I have a similar yellow result on the monitor after calibration. Did you find any different settings that helped?

I am using iMac 27" i7 and spyder as well. I don't have any problem calibrating the iMac. The only problem is that some of the iMac will not save the brightness settings and it will automatically resume to the brightest when reboot.

I once complained about the temperature of running W7 on the iMac, they checked my iMac and found minor issue with my display panel (some grey mark on the bottom on the screen), AppleCare voluntarily replaced the display panel for me. Then the diagnostic found an error message with the panel (which I used for 2 to 3 weeks without any issue), they offered to replace another new panel for me. Excellent service.

Why don't you try to contact them about the yellow color on your display, it might not be a spyder issue at all. Cheers.

I would try to calibrate to Native White point Kiav, that seems to help the color cast on IMacs.
As for the Spyder 2, I believe they are not compatible with the LED, High Gloss and Wide Gamuts, but the Spyder 3 generation of products is.