I downloaded the most recent version of the Wilderness theme and this problem has been solved. The author removed the styling from the Admin buttons that was the source of the problem. It's nice to have the Upload links back in the IMCE file browser, but I miss those really nice looking rounded buttons in the Admin interface. Would like to have those back :-)

I found a quick fix here:

http://drupal.org/node/543492#comment-1932184

but it also removes all the theming for the site admin buttons. Which I don't want to do. So I changed the font color of the site admin buttons from white to black using this css:

1. Find this code at line 952:

/* begin Button */
a.Button, button.Button
{
	display:inline-block;
	width: auto;
	outline:none;
	border:none;
	background:none;
	line-height:33px;
	margin:0;
	padding:0;
	overflow: visible;
	cursor: default;
	text-decoration: none !important;
	z-index:0;
}

Add this line:

color: #000;

2. Find this code at line 970:

a.Button .btn, button.Button .btn
{
	display:block;
	position:relative;
	float:left;
	height: 33px;
	overflow:hidden;
	white-space: nowrap;
	width: auto;
}

Add this line:

color: #000;

3. Find this code at line 994:

a.Button .hover, a.Button:hover, button.Button .hover, button.Button:hover
{
	color: #F1F8EC;
	text-decoration: none !important;
}

a.Button .active, button.Button .active
{
	color: #F1F8EC;
}

Change the font color to this:

color: #000;

in both places.

So now you can see the Upload button in the IMCE File Browser.