Edit in JSFiddle

var control = 0;

$(":checkbox").click(function(){
    if (this.checked) control++;
    else control--;

    if (control > 0) $("button").prop("disabled", false);
    else $("button").prop("disabled", true);
});

<section class = "labels">
    <label for = "uno">Check 1:</label> 
    <label for = "dos">Check 2:</label> 
    <label for = "tres">Check 3:</label> 
</section>

<section class = "checks">
    <input type = "checkbox" id = "uno" />
    <input type = "checkbox" id = "dos" />
    <input type = "checkbox" id = "tres" />
</section>

<button disabled>Botón</button>

.labels, .checks{
    display: inline-block;
}

.labels *, .checks *{
    display: block;
}

.checks *{
    margin: .5em 0 0 0;
}

button{
    display: block;
}