the kind where you need to find out the SE bot's IP address so you can feed it something strictly designed for high rankings
So user_agent cloaking is still acceptable to you? I'm relieved! ;)
It's all about tricking the search engines, as opposed to helping the users.
There's a thread here [webmasterworld.com] proposing the SEs offer an "uncloaking service," and a few responses. Reiterating one of my comments in that thread:
If cloaking represented a major source of irrelavent results in the SERPs, it would affect the SEs income and "bottom line" and they would have discouraged it years ago instead of doing lip service in their webmaster dos and don'ts pages.