This is my solution for this:
https://gist.github.com/BryanMoslo/808f7acb1dafcd049a1aebbeef8c2755
The element recibes a "tooltip-title" attribute with the tooltip text and it is displayed with CSS on hover, I prefer this solution because I don't have to include the tooltip text as a HTML element! 
#HTML
<button class="tooltip" tooltip-title="Save">Hover over me</button>
#CSS
body{
    padding: 50px;
}
.tooltip {
    position: relative;
}
.tooltip:before {
    content: attr(tooltip-title);
    min-width: 54px;
    background-color: #999999;
    color: #fff;
    font-size: 12px;
    border-radius: 4px;
    padding: 9px 0;
    position: absolute;
    top: -42px;
    left: 50%;
    margin-left: -27px;
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s;
}
.tooltip:after {
    content: "";
    position: absolute;
    top: -9px;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: #999999 transparent transparent;
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s;
}
.tooltip:hover:before,
.tooltip:hover:after{
    visibility: visible;
    opacity: 1;
}
" tag, the tooltip shows "foo
bar", you know what I mean? – gaetanm Jun 30 '13 at 14:16