Yep. Only a minor annoyance though.

the search flood thing is 15 seconds.
If it's really anoying I could see if I can disable it for the newposts check though

I don't think the root problem is the "search flood thing". When I check the HTTP-headers (using the Web Developer plug-in for Firefox), I see the following:

1Response Headers - http://www.vogons.org/search.php?search_id=newposts
2
3Proxy-Connection: Keep-Alive
4Connection: Keep-Alive
5Date: Fri, 23 Jun 2006 16:29:21 GMT
6Cache-Control: private, pre-check=0, post-check=0, max-age=0
7Expires: 0
8Pragma: no-cache
9Vary: Accept-Encoding
10X-Powered-By: PHP/4.4.2
11Transfer-Encoding: chunked
12Content-Type: text/html; charset=UTF-8
13----------------: ----
14
15200 OK

I think it is the Expires: 0 (expire immediately) combined with max-age=0 and Pragma: no-cache that causes the browser to re-post the search URL even when all I do is to use the back-button in the browser.

(while I investigated this, I found these two cache-testers: http://www.ircache.net/cgi-bin/cacheability.py, http://www.web-caching.com/cacheability.html)

Perhaps it would be possible to set the expire time to something like 60 seconds for all searches?

All phpbb2 based boards sets these headers.