RadRails is getting company from commercial player ActiveState that has recently shipped Komodo 3.5, their IDE for dynamic languages. Komodo features support for Ruby and Rails and is available on Windows, Linux, and Mac OS X.
Komodo Professional is a $295 buy, Komodo personal is $29.95, and there’s a 21-day trial available.
The release got a bit of play in the press with an InfoWorld article called Ruby IDE is set to shine.
Being a OS X/TextMate user myself, I haven’t had a chance to checkout Komodo. Please do add your experiences in the comments for others to share.