The correlation coefficient for the Power fit shows the correlation between the Power curve fit and the original data. Some other programs show the correlation between the Linear curve fit and the log of the data. That is why when you apply a linear fit to the logged data in KG, you get the same R value as some other programs report for their Power fits.
KaleidaGraph is a thoughtfully designed graphing and data analysis application for research scientists, as well as for those in business and engineering fields. It produces publication-quality graphs, and easily converts the most complex data into a functional display.