I used to use Lightbox 2 plugin from Rupert Morris. However, up to today, this plugin is still not compatible with WordPress 2.5.1

But the good new is, the alternative one works just fine. If you want to add cool Lightbox to your WordPress and don’t want to wait for update, do the following:

1. Install Lightbox-auto. (optional)

This plugin for Wordpress automatically add the rel=”lightbox[ID_OF_THE_POST]” to images linked in a post. So you will never have to add rel=”lightbox[ID]” when you write a new post.

2. Install Wp-lightbox. (Required)

The alternative of Lightbox 2. It is a plugin that turns linked images into neat Javascript-powered overlay popups.

3. Install Flexible Upload. (Optional)

Flexible Upload is a plugin for Wordpress 2.0.x, 2.1.x, 2.2.x, 2.3.x and 2.5 to enhance the image upload functionality.

For wp-lightbox, in order to see the “Previous” and “Next” links, you will need to tweak line 45 of the lightbox.css file to read width: 45%

Here it is inline:

#prevLink, #nextLink{
width: 45%;
height: 100%;
background: transparent url(../images/blank.gif) no-repeat;
display: block;
}