Not only does Lightroom not have the option to sharpen images, it is also exporting HTML files with incorrect information. I created a web gallery using the Midnight template, set the Preview setting to 600 (large images) and exported the web gallery. All of the vertical images have been resized to 599, while the value for the height attribute in the img tag is set to 600. As a result of this inconsistency in the actual size of the image (599) and the height attribute (600) the images look considerably distorted.
Iíll be sticking with Photoshop for creating web galleries until Lightroom provides the ability to sharpen images and at least produces accurate HTML code and properly resizes images.