g1smd - 10:58 pm on Mar 14, 2010 (gmt 0)
I've also recently dealt with a site where there were supposedly incoming external links pointing to /index.html but on inspection they were all found to point to / instead.
I am not sure if that is indicative of some other problem or not.
I use redirects quite a bit. One recent case was for a site where the internal links all pointed to non-www URLs, but all incoming external links pointed to the www version of those URLs.
Google had already listed mostly non-www URLs for the pages of the site, but had listed several www URLs for some of the content. Most importantly, the root index page was listed as ONLY a www URL.
All of the internal links were then changed to point to www URLs, and a redirect was also installed from non-www to www. It took less than two weeks for Google to add the www URLs to the index, and a number of non-www URLs remain in the SERPs some three months later.
So, in this case, redirects are an important part of the fix. However, I do see a large number of sites where poor redirect implementation adds to the problems rather than fixing them all.