Thule is using Firebird and Firebird .NET Data Provider
Thanks to Steve Ramacher, who sent me this info.
We run our business on a couple of AS400 mid range computers (we are in the process of converting to MS Dynamics AX). We use BPCS for out ERP system. 7 years ago we started running into situations where we need to archive our reports to externals servers. This included reports that are ran daily and invoicing.
We started with SharePoint services but quickly out grew the capabilities of SharePoint (in regards to what MS indexing server could do). I wrote a role based security web site using firebird as the backend. I then wrote an administrators console to that allows Administrators to add/remove users, control there access, deploy smart client programs, and view reports.
The next task was very cool, I use MS DTS services (runs as a job in system agent) to extract data from our AS400 (DB2) and load the tables in our firebird server (running on windows). From that I am able to power our invoice lookup. We spool 1500+ invoices a day for orders through a product called reform which creates a PDF version of the output at the same time that it prints the spool. I wrote a program that matches up the customer, tracking, shipping to the invoice. So we have a customer service application (Smart Client) that they are able to lookup post shipment invoice information (Printed invoice, customer information, tracking information, proof of delivery, etc.) all being powered by Firebird and the .net providers.
I have used this provider with data tables, datasets, and custom collections with absolutely phenomenal success. Over the years I have upgraded the sites to include the new features of you provider (roll provider etc). I mostly write custom collections so that I can control my CRUD operations. If the power of linq makes it to firebird, that would be amazing.