interesting.. google wouldn't ban you for that..unless the links themselves are in bad neighborhoods , or from spam looking systems like power links, etc.
i really doubt it would ban you even then I have built some really spammy sites and only a handful have ever been banned
If the site is relatively new and creates over 700 links per month will make problems. I have noticed it several times. You will see backlinks droping day by day for such sites.
How where the SERP's though. I have had sites rocket to PR6 also, but the SERP's dropped as I seemed to grow the site to fast.
I feel quite ok about SERPs. I didn't do much work for that site - just some content (which was not really optimized, i.e. I held no onpage optimization) and these 500 links... Now I'm on the second page at Yahoo and MSN for my main keyword
The problem is that the site I was experimenting with is completely new (3-months-old for now), so it's definitely in Google's sandbox for now... That is why I wouldn't dare take google's results into account
Take this with a grain of salt, but I read that Google doesn't care how fast you get your links. I mean that if you had $4,000,000 and took out a couple Super Bowl commercials, you will probably grow a lot faste than I do when I spent $400 on a site. The way I understand it, they watch for irregular growth. So if you get 200 links in one day and don't get any more in the next 5 monthes, they know something is up. Even though the Super Bowl ad would generate quite a few links quickly, you will still see links coming your way for the next year to come. Whether this is wrong or right, it sounds logical and it's what I try to do. Brandon