My MAIN FILE from /var/log/dist-upgrade (numerous attempts to finalise updating Feisty and jump to Gutsy ends with that same "nothing" (before end of support 7.04 I did that easy, but unfortunately I lost my system, so after re-installing Feisty I suddenly faced this problem).
Location - Russia, System - notebook based on Via motherboard with AMD Sempron 2600+,
Ubuntu 7.04  for i-386 

2009-02-18 01:51:23,163 INFO release-upgrader version '0.81' started
2009-02-18 01:51:23,651 DEBUG lsb-release: 'feisty'
2009-02-18 01:51:23,652 DEBUG _pythonSymlinkCheck run
2009-02-18 01:51:25,357 DEBUG checkViewDepends()
2009-02-18 01:51:25,358 DEBUG getRequiredBackports()
2009-02-18 01:51:26,029 ERROR IOError in cache.update(): 'Failed to fetch http://ru.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found [IP: 77.88.19.74 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/restricted/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/main/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/multiverse/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/universe/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
'. Retrying (currentRetry: 0)
2009-02-18 01:51:26,599 ERROR IOError in cache.update(): 'Failed to fetch http://ru.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found [IP: 77.88.19.74 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/restricted/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/main/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/multiverse/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/universe/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
'. Retrying (currentRetry: 1)
2009-02-18 01:51:27,211 ERROR IOError in cache.update(): 'Failed to fetch http://ru.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found [IP: 77.88.19.74 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/restricted/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/main/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/multiverse/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
Failed to fetch http://archive.ubuntu.com/ubuntu/dists/feisty-proposed/universe/binary-i386/Packages.gz 404 Not Found [IP: 91.189.88.45 80]
'. Retrying (currentRetry: 2)
2009-02-18 01:51:27,212 ERROR doUpdate() failed complettely
2009-02-18 01:51:28,982 ERROR Can not find backport 'release-upgrader-apt'