I have heard that if you wire transfer money (some say more than $800, some say $10,000) back home, you are noted by fed and that could cause a potential delay on your future greencard/citizenship application. How true is this? I tried looking up with the amount is and cannot find anything related to this via google.

Anyone knows?

Not sure. I once sent 40G's about 6 years back no problem so far. Even got GC last year.

This, at the best, is your typical Gorkhe paranoia. Yes, the financial institutions do have to file transactions exceeding certain amount (I think it's 10K) originating from a given individual with the government. The reason for such a regulatory requirement is to keep track of funds movement that may end up financing terrorism related activities. It would be a serious waste of government resources if they waste time/money tracking personal information as such for greencard processing.