Another attraction is that Rails embodies many of the principles of agile software development, said Lugrin. With its focus on writing tests before code, it helps programmers working on projects where the requirements are changed and refined during the course of development.

At the Paris on Rails event, two businesses presented projects developed in Ruby on Rails.

Aurélien Géron of Wi-Fi hotspot operator WiFirst explained how his company had chosen Ruby on Rails over Python to develop a site offering e-mail, photo hosting and contact management. "There were already lots of libraries available for Python," he said, but in the end it was the dynamic development community around Ruby on Rails that carried the day.

RBC Dexia Investor Services, a bank, explained how it is using Ruby on Rails to make better use of its existing Java application infrastructure.

The conference, now in its second year, drew 240 developers and project managers. That's about half the number that attended a conference aimed at users of rival Web programming language PHP here last month, the Forum PHP Paris.

The difference underscores a complaint common among businesses using Rails here -- there aren't enough available Ruby on Rails programmers around.

"France is historically one of the countries where PHP is strongest," said Piacentini.

Getting Rails into the hearts and minds of more developers will be the next challenge, then.

That might happen with the attention being paid by big players such as Sun and Microsoft -- or even Apple, which included the software in Leopard, the latest version of Mac OS X.

"When you buy a new Mac, Rails is right on the development tools CD," said Hansson.

Some will take little persuading. Many of the speakers, and most of the front row of the audience at Paris on Rails, were already carrying either a MacBook or an iPhone.