> What's the penalty if google finds 20 or so sites sitting on the same Ip crosslinked?
Well rudy, it probably depends on what you mean by crosslinked. If each of the 20 sites links to each of the other 19, then your network sounds very similar to those that were given the "PR0" penalty (where Google ignores all incoming links to that page/domain). The site search [searchengineworld.com] will probably give you rather more information than you require if you search for PR0 or PageRank zero. This is because it's sometimes hard to tell what's happening, because people often mistakingly think they have a penalty for a particular reason (or at all); and because the exact rules are complex (and not just about crosslinking, though it seems to be the most common element).
Google don't want people to learn their automatic penalty rules and bypass them for spam. One thing I'm pretty sure about is that you would not be protected if you had 20 different IPs. There have been reasons to suspect that IPs might come into automatic penalties, but I personally do not believe that Google does this.
> Will I be ok on the next index if I uncross them for the next crawl?
If you have been given an automatic penalty (i.e. the Toolbar PageRank graph is all white, even though pages with good PageRank link to the exact same URL) then it's hard to say how long you'll keep it. Some people have been getting their PageRank back pretty quickly recently, others have waited a long time.
If you are missing (i.e. the Toolbar PageRank graph is grey, you don't come up in the searches at all and a search for your domain comes up with "Sorry, no information is available for the URL ...") then it's most likely not a penalty. One thing to check is whether a search for your domain includes the text "If the URL is valid, try visiting that web page by clicking on the following link". If it does, then it's not likely to be a penalty.