Updates of MEXNC, SNCTOOLS, and the NetCDF Toolbox are now available for R2008b. Instead of offering them separately, they are now bundled together since changes were required to each one to get them ready for R2008b. Details for each are somewhat different, so please check their respective READMEs. I did quite a bit of testing to make sure that the extensive test suites for MEXNC and SNCTOOLS are ok (with a few exceptions) on R2008b, but it's quite possible that I've missed a case or two. If you find that you have code that used to work in R2008a but causes errors with R2008b, please try to narrow down your problem as far as possible and let me know.
Please note that neither SNCTOOLS nor MEXNC nor the netcdf toolbox are supported by the MathWorks, so please do not ask the MathWorks for support regarding them. Also note that I did not write the netcdf toolbox, so I can't give much of any support to it. Yes really. If you have questions about SNCTOOLS or MEXNC, please continue to use the contact email address listed on this site.
MEXNC is a mex-file interface to NetCDF files for MATLAB, and has roughly a one-to-one equivalence with the C API for NetCDF. In fact, there's no better introduction to MEXNC than to read the NetCDF User's Guide for C provided by Unidata. It currently compiles with NetCDF library versions 3 and higher, and if it is built with 3.6.0 or higher, you may get the benefit of Large File Support if your OS supports it. Here's a general overview of mexnc.
MEXCDF was the original name for the mex-file interface. Well, actually it used to be "mexcdf53". When the NetCDF-3 API was incorporated into the mex-file, it was suggested that "mexnc" would be a much less confusing name for the mex-file itself, and so a name change was instituted. MEXCDF remains as the umbrella name for this sourceforge site and all the m-file software related to the mex-file.