You shouldn't invoke latex (or pdflatex) from the folder that contains the executables, because that folder is (or at least should be...) writeable only by root. Thus, latex has to crash because it can't create the .log, .aux, and .pdf (or .dvi) files to the executables folder. You may verify this by typing
sudo ./latex /Users/fluid/Desktop/sample.tex from within the executables folder, viz., /usr/local/texlive/2010/bin/x86_64-darwin: you'll be prompted for the superuser password, and thereafter latex should run without further complaints of the type you report in your posting. BTW, I really don't recommend doing this (i.e., running latex with superuser privileges) on a regular basis.
Assuming MacTeX was installed correctly, the TeX executables should be in the search path, and you should simply be running latex from the folder that contains the .tex file -- in the case you report, the Desktop folder.
By the way, you may want to think about updating your TeX distribution to MacTeX 2012.
