Recently, I've been looking into developing for the mobile platform. In particular I wanted to develop an application for the iPhone - it seems to me that if you're going to get a large audience, then Apple's AppStore is the place to be. There was part of me that felt uneasy about this. After all, I was turning my back on other platforms, particularly Android.
Right now, the mobile device targets are iPhone and Android, with iPad and Blackberry support on the way (and available from the Beta program). The free version allows developers to get a feel for Titanium with all the features of the paid Professional version ($199 per developer per month). There is no product different between the different versions: the differences surround the support SLA, length of analytics data and the ability to get early access releases.
Have you used any of these cross-compilation tools for developing mobile applications? Do they work well, or is there a catch? I'll be taking a closer look at Titanium over the next few weeks and will report back on how the experience went for me.