You wait and watch! The trial has already began - Wait to watch the real match. But this time its gona be more specific and Matt Cutts is trying to be open. Have your any site affected? 2 key phrases? medium competition?
Panda, Penguin, Wolf...and panic in the Zoo))) I don't really worry about new updates, cause my site seems to be safe. I work hard on it. However, Google surprises every time...
I try to follow their rules as well but you never. For example, I had a number of Exact Match Domains (EMD), sites built on them, good content, strong backlinks but at that point they decided that they didn't like the site because of my domain name and bam I was gone. I then registered new domains and did a 301 redirect and I was back to almost the same spot. My point is that you can do everything right but they do one change and your gone.
blackhat practices will be the end (i doubt)... as saying: "as long as blackhat is alive, you can be rank"
Throwing fish for penguin as gratitude is good idea. Just make sure not to throw a hungry shark. Penguin wouldn't eat the fish, but the fish would eat the penguin.
Content is one of the most important part, so replace the duplicate content quality and unique content.
Well, don't worry of this, instead of decrease in ranking, your ranking would increase as well, if you are doing quality works......