I've never developed in Eiffel but I've met people who have. Eiffel is promoted in Dr. Bertrand Meyer's book: Object-Oriented Software Construction, 2nd Edition.

I do expect that methodologies for software engineering and development will continue to mature as time goes on and it looks like Eiffel will have a role in this.

Also, I found this news item at www.eiffel.com

Bill Gates praises Eiffel to 7000 Windows developers

July 12, 2000

Eiffel was featured prominently at the 10th Microsoft PDC (Professional Developers Conference) in Orlando this week, described by Microsoft officials as the most important event since the first PDC introduced Windows in 1991. Among the major innovations of the .NET framework introduced this week is the ability to combine languages in a completely seamless fashion, including cross-language inheritance and cross-language debugging. Eiffel is one of the first languages supported in this new architecture.

Talking to 7000 cheering Windows developers, Microsoft Chairman and Chief Architect Bill Gates praised Eiffel as a "very innovative language" and introduced Dr. Bertrand Meyer, President and CTO of Interactive Software Engineering. Meyer described the language interoperability advances of .NET, which he called "unprecedented", and showed how Eiffel provides .NET developers with the support they need for mission-critical applications in e-commerce, the financial industry, simulation, real time, health care...