I recently played around with Azure web sites and wanted to analyze the IIS logs generated by azure but none of the tools I tried could parse the file I downloaded. Turned out that the header line of the file that looks like this:

# date time s-sitename cs-method ...


That is apparently not correct W3C log format. once I change the line to this:

#Fields: date time s-sitename cs-method ...


With that change all the tools I tried were happy with the log files.