Just after I converted script.aculo.us to be used woth Drupal, here’s my version of Lightbox2 I just provide the js, please catch the rest on the Lightbox2 homepage. I can not really say, if it works, because I haven’t tested it (there was no ‘rake test’-testuite 
). I was a long time user of Lightbox, but when I started to care about licences(I want to release some opensource scripts soon) I noticed that Lightbox2 is released under the CC-By 2.5, which GNU declares as GPL-incompatible, so I moved to Thickbox which works on the basis of jQuery which is much better when using Drupal (you need to load less javascript files).
As already known, here the 2 version of Lightbox2:
technorati tags:javascript, prototype, script.aculo.us, lightbox, lightbox2, drupal, thickbox, jquery, jsjuicer
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Well done on your contribution to the project so far. I am the author of the LightboxV2 module and will look at integrating your changes as soon as possible.
Incedentally, with regards to your comment about licensing. When I first created the Lightbox module, I contacted the original author of the Lightbox Script (Lokesh) and got permission to distribute the Drupal customised version of Lightbox under a dual license (similar to the manner in which Jquery is distributed with Drupal).
However, your comments about the difference in scripts is valid - te existence of Thickbox is the reason I haven’t put too much effort into the conversion of LightboxV2 for Drupal 5.
Once again, many thanks for all your effort. I am sure you will have made a lot of people happy.