I stole the code posted on reddit earlier today and ported it to ruby. Now I can do the following:
layout = BoxLayout.html <<-END
----------
| |
----------
| | | |
| | | |
| | | |
| | | |
----------
| |
----------
END
puts layout % [header, left_sidebar,
body,
right_sidebar, footer]
and get layout code that looks much much cleaner than the equivalent HTML/rhtml/whatever. I can instantly look at this code and know what it is gonna look like in a browser. I'll release this soon, but I have some enhancements for codeforpeople's rubyforge and seattle.rb's hoe first.

Does this spit out css layout styling or layout via tables?
i am extremely excited by this. the sooner you release this (in any state) the better.
That's pretty cool, and would be even cooler if HTML table layouts still were all the rage nowadays ;)