Centering a floating div

This is not a fixed width layout. I have one or two CSS techniques applied to these images– a shadow for all of them which requires floating, and there is also a caption for some of them.

[url]http://matt.mw/gmsaa/articles/passing_in_review3.html[/url]

I need to be able to center the last picture “with” the shadow in this layout, but am wondering how to do this. I managed to do it with two images (as you can see at the very top) using 2 divs within another div, but one image is really killing me with floating items.

[CODE].img-shadow {
float:left;
background: url(http://matt.mw/gmsaa/img_shadow/shadowAlpha.png) no-repeat bottom right;
margin: 10px;
}
.img-shadow img {
display: block;
background-color: #fafafa;
border: 1px solid #a9a9a9;
margin: -6px 6px 6px -6px;
padding: 4px;
}

<div class=”img-shadow”><img src=”http://matt.mw/gmsaa/articles/passing_in_review/passing_in_review_images-012.jpg” /></div>[/CODE]

[B]
So without taking away this float & shadow, how do I place this image in the exact center when this layout is not fixed? [/B]Obviously text-align:center has no effect on floating items. Seems different positioning methods like “absolute” ruin my shadow.

Please help me out! Thanks.

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