Hmm...time to do a little detectiving.
The current S-6, Andrew, Jan 08 thing seems to come from some fan's journal page at Bebo.com. Where did he come across the info? Who knows? I can guess though.
I first started hearing the Ripper talk sometime around Season 7, so it's been around at least since then. There have been claims that later turned out to be bogus. Before there was TV.com it was called something else, TV Tome I think. They claimed Ripper had a production date the following summer. That was shortly after Season 7, so the claim was obviously bogus. That was also where I first heard of the Season 6 Ripper thing, I think. With the Andrew thing I remember the original rumour said Ripper's companion was going to be Whistler from Becoming 2. Somehow that morphed into Andrew, but I also heard the Andrew one before this current session of Ripper talk.
The only truly credible, current, Ripper claim I know of is the suggestion from Joss which we see at the beginning of this thread. If anyone can post a link to something more detailed from a credible source it would be great to see.
As a far as a "canon clash" goes though, it's a little early for that claim don't you think. We don't have any credible details as to when Ripper is going to take place, or what's going to be happening in it. Or at least I don't. If somebody does, link please.