Doing headless integration testing really is superior. Requiring one machine per concurrent test isn't scalable. Sure, works great for your weekly/daily test. But if you want integration testing to run at every commit it's not going to work.

I've done some experimenting with Celerity (headless integration testing with JS support) and it works quite well. Can even emulate CSS and it scales much better. One thread becomes one test. So running 50 tests in parallel on one machine is no problem. This really is a requirement for me if you want it to work with CI.

Celerity is based on Watir (similar to Selenium) and Ruby. See http://celerity.rubyforge.org/

With regard to b) support for languages other than AppleScript, ruby and python support is likely to work through Apple's Scripting Bridge.

Most AppleScript aware applications can be made to support ruby and python through this bridge:

http://developer.apple.com/mac/library/documentation/Cocoa/C...