Hey Todd,
That would be great if you have time/interest in trying to get a VistaDb data layer going! In theory since they closely suport the same syntax as MS SQL it may be a matter of copying the MS SQL data layer and doing a find and replace to switch to the ado.net components for VistaDB.
If you do give it a try, just let me know anything I can do to help or be supportive. Once an intial version is implemented I can keep it maintained and could create some Codesmith templates for it like I have for all the other db layers.
Best,
Joe