The Thickbox script is getting old and when I was looking around for something to replace it I found the Colorbox script.
I propose we port over all the features from the Thickbox module and contemplate making Colorbox 7 the upgrade path from Thickbox 6.
This new version of Colorbox should be able to be a drop in replacement for Thickbox as long as you can run jQuery Update version 6.x-2.x.
A neat feature would be a update function that change the display settings for all CCK content types from Thickbox [preset] to Colorbox [preset] automatically. That would make it a true drop in replacement.