On Azure itself, I find I can make blobs with names of length 1000, but not 1100 (so I guess 1024). Using dev storage I can do 200, but not 300 (so I guess something related to MAX_PATH). Is there an official limit?
From http://msdn.microsoft.com/en-us/library/dd135715.aspx:
A blob name can contain any combination of characters, but reserved URL characters must be properly escaped. A blob name must be at least one character long and cannot be more than 1,024 characters long.
The Azure Storage emulator supports blob names up to 256 characters long.