Hi Kenny,
There is not any current functionality to do this, but at some point I may build a utility for it. Its not as simple sql as your illustration because there are identity columns to consider.
Probably the easiest approach is to restore a backup of the whole db then delete the extra sites. However, moving db content from one installation to another is problematic if the url is going to be different in the new location, if the url is going to be the same its not too bad. What I mean is if the first installation has the site at http://www.somedomain.com and it will be the same on the new installation all is well, but if its going to be a different domain or a sub folder is either removed or introduced to the url like from http://www.somedomain.com to http://www.somedomain.com/somefolder its a problem and if it was http://www.somedomain.com/somefolder and now its going to be http://www.somedomain.com its a problem.
The reason its a problem is because the html content in the db probably contains full links in some places for images or other content links and these will be broken if the url changes, or will still point to the old location in any case. Some features in mojoportal use relative urls for images, like the Html feature, but others like th eblog use fully qualified urls for images. This is needed for any content that is exposed via rss, otherwise the images won't display in the feed.
Hope it helps,
Joe