How does HTML mouseover work on apple multitouch devices?
The way around this is to use a mouseover handler on a "clickable element", as Apple explain in their Web Content Guide:


  Mouse events are delivered in the same
  order you'd expect in other web
  browsers [...]. If
  the user taps a nonclickable element,
  no events are generated. If the user
  taps a clickable element, events
  arrive in this order: mouseover,
  mousemove, mousedown, mouseup, and
  click. The mouseout event occurs only
  if the user taps on another clickable
  item. Also, if the contents of the
  page changes on the mousemove event,
  no subsequent events in the sequence
  are sent. This behavior allows the
  user to tap in the new content.


Tapping once on a clickable element that has mouseover/mousemove content displays that content.  Tapping a second time does mousedown/mouseup/click.

A "clickable element" is:


  a link, form element, image map area,
  or any other element with mousemove,
  mousedown, mouseup, or onclick
  handlers.


Therefore to fix the spoiler rollovers they would have to change using CSS to Javascript (i.e. use a mouseover handler on the blockquote, rather than a CSS class).

(Apple has patent applications for detecting hovering on touch interfaces, so this could go away in the future.  However, it's unlikely that will be soon).