Waiting with a block 06/08/2012
# Waiting until a condition in the block is true. In this case until a DIV with ID of 
# navigation to be visible.
Watir::Wait.until {
  browser.div(:id => 'navigation').visible?
}

# A timeout can be provided here too
Watir::Wait.until(10) {
  browser.div(:id => 'navigation').visible?
}

You can define a block to wait for specific conditions, which by default timeouts after 30 seconds. This can be useful when waiting an element in some other part of the page before acting on an element.