That rule will take whatever you have after the domain name and append it on the end of ht*p://www.newsite.com/. So if you have ht*p://www.theoldsite.com/one/two/three.html it'll redirect you to ht*p://www.thenewsite.com/one/two/three.html
To redirect from any page on the old site to a single page on the new site, use the following:
Code:
RewriteEngine ON
RewriteRule ^(.*)$ http://www.thenewsite.com/something/blah.html [R=301,L]