These are all nicked from Matt White's pages.http://mattwhite.me/blog/2009/6/27/how-to-add-non-breaking-spaces-to-your-xpages.html
You cannot use nbsp; in the source of an xpage as it is not compatible with xml.
You can put in   which is the ascii digital code for a non breaking space. these codes can and should be used in xml.
Another tip is if in the Design mode of the xpages designer you can add a non breaking space by doing a CTRL + spacebar.