css text float

HTML

<div><span class='a'>a - text</span><span class='b'>b - some really long text and stuff</span></div>

CSS

div{
    width:150px;
    border:1px solid #FFF;
    overflow:hidden;
}
.a{
    float:right
}

.b{
    display:block;
    overflow:hidden;
    white-space:nowrap;
    text-overflow:ellipsis;
}