Try this:

http://jsfiddle.net/WTNeB/2/

notice that i added display:table and display:table-cell but also I changed the css selector names so that it gets the priority needed.

.row-fluid {
    border: 1px dotted gray;
    display: table;
}
.row-fluid .span2 {
    border: 1px solid blue;
    display: table-cell;
    float: none;
}
.row-fluid .span10 {
    min-height: 100%;
    border: 1px solid red;
    height: 100%;
    display: table-cell;
    float: none;
}