Treyarch has explained to the Call of Duty: World at War community why patching the PC version has taken so long.
The conclusion of a lengthy post by community manager JD_2020 (Josh Olin according to Kotaku) is that desktop updates take a minimum of eight weeks from start to finish.
This process involves listening to fans, reproducing the issues to engineers, testing, submitting the patch to Activision, more testing, and then finally building an installer and distributing the files.