Matt Cutts in an update to this post says "We saw so many urls suddenly showing up on spaces.live.com that it triggered a flag in our system which requires more trust in individual urls in order for them to rank…". Now, I might be misinterpreting this statement, but it sounds to me like a confirmation that adding too much at one time will trigger a flag. It's possible that just adding too many new subdomains causes a problem, but I would guess it may apply to pages or folders as well.
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I don't think you're misinterpreting at all, Donna. This kind of thing was mentioned in various circumstances a couple different times at SES San Jose — whether it's links, content generation, or just about anything, "too much too soon" sends the wrong signal to the engines. Moderation is really important to the degree you can control it. If you appear on Oprah or CNN, the engines will adjust.
Although we've all "known" it for quite a while, it is just so rare to get it from the horse's mouth (not that I'm calling Matt a horse of course of course). Every time we get an actual glimpse into the algo, we gain a little something. Were any of those various circumstances at SES San Jose actually from a Google rep? Just curious.
[...] My Mom was an SEO Pioneer By Matt McGee There's a lot of talk these past couple days about some recent comments Matt Cutts of Google wrote on his own blog. [...]