Well, I didn't like any of those answers, my solution of the same problem was to add this:<div> </div>
. So in your scheme it would look like this (more or less), no style changes were necessary in my case:
-row-fluid-------------------------------------
+-span6----------+ +----span6----------+
| | | +---div---+ |
| content | | | & nbsp; | |
| that | | +---------+ |
| is tall | | +-----div--------+|
| | | |short content ||
| | | +----------------+|
+----------------+ +-------------------+
-----------------------------------------------