Twist is an Integrated Development Environment (IDE) for functional testing. Selenium is an open-source web application testing system also started at ThoughtWorks.
Twist uses an enhanced version of Selenium ("TwistSelenium") to drive web application testing. The TwistSelenium driver has many fixes on top of Selenium, and adds critical functionality such as a recorder.
Twist supports functional testing of Java Swing applications and Web applications (including Ajax based ones) as of now. The Scenarios are implemented in Java.
Twist is a Java-based product and therefore runs on Windows, Linux and Mac OS X.
Ruby support is slated for a future release.
Yes, you can record a scenario using Twist. Twist supports recording of Java Swing applications and web applications (including Ajax-based ones). Please note that Twist does not support recording in IFrames in Web applications as of now. For detailed help on Twist, read our Help Pages.