W3C recommends putting a space before the closing tag in XHTML, because this would give a better backwards compability with some browsers, e.g. write
I would say no... It was to support Netscape 4, as bobince said, and I believe the number of such browsers being really in use is very near zero, fortunately!
Unlike what Vincent said, I don't think IE4 has such issue. And I believe we can class IE3/4/5/5.5 as dead anyway (at least gone of Web statistics), and waiting impatiently to do the same for IE6 too! :-D
Silly thing, this has influenced so many people that sometime I see x="foo" />
even pure XML files!
It's for Netscape 4.
I still include it out of habit, and my templating library will put them in for me anyway, but it's questionable whether it's really that important today.
The point of backward compatibility is to still support the browsers that do NOT support the short notation. There's probably still a lot of those out there.
I guess your choice might depend on the target audience of the website (e.g. a tech site will have more visitors using a recent browser, as opposed to seniors.net, visited by people using Win 95 and IE 4).
If there are still browsers that rely on the space use it.
The amount of bytes saved does not justify the possible problems.