It appears that PromptSQL has been purchased by Red Gate Software. I haven't seen a news announcement about it, and there's nothing on the acquisition on the Red Gate site itself, but both of the following links indicate Red Gate now produces SQL Prompt (which matches with the naming convention of other Red Gate software):
The news on the site inducates they are shooting for a May 2006 release
date (the version they are working on is considered beta) and existing
Atadore customers of PromptSQL will be upgraded for free.
IT Security, MySQL, Perl, SQL Server, and Windows technologies.