EDIT: i just looked at your code, you'll actually need to apply the float:left; to your <iframe> tag that you have & the <div> you have for your facebook button.
Code:
iframe{
float:left;
}
.fb-like fb_edge_widget_with_comment fb_iframe_widget{
float:left;
width:150px;
}
You also need to change the width of your "fb-like fb_edge_widget_with_comment fb_iframe_widget" <div> because it's sent to 450px right now, which is causing the button not to float since it cannot fit on the line above it. If you reduce the width to about 150px you should be fine.