Quest Software offer a SharePoint migration tool, which can migrate SharePoint 2003 to 2007 and 2007 to 2010.
Quest enables remote migration by offering a web based console that can be accessed from any web browser. It also helps you to easily manage your migration project with the use of, pre-migration assessments, migration job controls, real time progress reporting and scheduling.
Quest will migrate SharePoint sites including content and security settings directly to the new platform. It also enables you to reorganise your site structure during the migration process. Once the migration is complete you can also update any changes to the original sites on the target sites. Quest can even migrate any customisation you may have on your sites including web parts.
Quest also offer a tool that states it can migrate SharePoint 2003 to 2010 directly without the need to migrate to the interim 2007 version. This can be seen in this video “Migrating SharePoint 2003 to 2010“.
More on this can be found at: Quest.