GitHubs like behavior for Twitter Bootstrap labels.

bs-labels-css-truncate.css

span.label.css-truncate {
  max-width: 80px;
  display: inline-block;
  overflow: hidden;
  text-overflow: ellipsis;
  vertical-align: middle;
  line-height: 1;
  padding: 2px 3px;
  height: 11px;
}

span.label.css-truncate:hover {
  display: inline;
  vertical-align: baseline;
  padding: 1px 3px 2px;
}