I've got a coworker/manager/stakeholder who is very conservative when it comes to adopting new technologies. I completely understand why: we have a lot of internal expertise with Java, MySQL/Postgres, and so on, they're well-established, and there's lots of good support for them.
But technology evolves, and sometimes newer technologies are better suited to today's tasks. It makes sense, for example, to do heavy numeric processing in something like Python+Numpy. Some kinds of simple web sites are faster and easier to implement in Ruby/Rails. Processing hundreds of gigabytes of logs a day is well suited to a Hadoop M-R architecture.
How do you work with people like this to overcome these kinds of objections?