The problem that I have with busy lists is that if you get behind in reading them it can look like a daunting task to see 100 conversations/threads (as in gmail) waiting to be read.
Site note: Filtering email lists in Gmail is really easy. There's a 'list:' modifier. So you can do 'list:python-list' if you've signed up to the mail python mailing list. Filtering them in procmail can be a PITA if you're trying to make a generic rule to filter list traffic into aptly-named folders, especially when traffic goes to two lists (e.g. python-announce and python-list).
Site note: Filtering email lists in Gmail is really easy. There's a 'list:' modifier. So you can do 'list:python-list' if you've signed up to the mail python mailing list. Filtering them in procmail can be a PITA if you're trying to make a generic rule to filter list traffic into aptly-named folders, especially when traffic goes to two lists (e.g. python-announce and python-list).