Now that Railo has finally opened up I think it is high time we take stock in the CFML landscape. What follows is how I view it with (of course) my personal twist/insight in each engine. I've tried to keep my personal commentary to a minimum, or at least hold it off till the end.
Open BlueDragon is GPLv3. It is the most open system with the most open development, though I think we could improve some. Anything that comes from OpenBD is GPLv3 or compatible. It is extensible but currently does not offer any store or other automated mechanism to add the extensions to the engine (though it is not hard and it is documented). So long as a commercial extension does not try to package and distribute the entire engine there are not problems with commercial extensions. Open BlueDragon is backed by a AW2, not New Atlanta. AW2's business model does not rely (primarily) on the CFML engine, though they do leverage it in some of their work from what I understand. When OpenBD was announced the project tried to gain confidence from the community by include some high profile names in the project steering committee (personal observation: BlueDragon had a bad name due to some old NA bad blood with Adobe and many were skeptical).
Railo is LGPL (sorry I can not remember the version I think 2 but maybe 3). It is mostly open. The core offers compelling compatibility and an astounding set of functionality. It is extensible via an app store type model where modules can be added onto the engine (I have not done enough looking to see if this is still manual or automated through the admin). Railo itself plans to make some functionality for pay. Railo the engine is backed by Railo the company and the business model s structure entirely around the Railo engine (services and product sales). Railo has positioned themselves inside the CF community as a competitor to Adobe by sponsoring CF centric events and hiring prominent figures in the CFML community.
ColdFusion is currently the most closed (in terms of source and openness to talk about what is being worked on). It is commercial and when you pay you get the whole kit and caboodle. ColdFusion can be extended through a couple of different means but not quite as tightly integrated as Railo or OpenBD at this point (the main extension point at the Java level is through CFX tags). ColdFusion is the original engine to use CFML and has gone through 2 acuisitions. It's a steady income for Adobe, they care about the CF community and do their part to keep it alive and happy (it is after all steady income for them).
To Adam Lehman's credit I think the information about CF9 has been much more open than previous releases. Don't take this comment too lightly this is a large shift for a large corporation. This comes from some one involved in many previous releases of ColdFusion and I personally see a huge difference in this release. The last couple of releases of ColdFusion have been driven heavily by the community. This is good but at the same time, the community is not full of big thinkers and typically we ask for functionality we need right now. This has resulted in stagnation of the ColdFusion platform, sure it has kept up but it has not PUSH forward much. Let's face it while Adobe (and Macromedia before them) have done a stellar job developing a great product the whole platform itself has sort of dwindled as they have focused on the language too much (not saying the platform has not grown it has but more evolutionary than revolutionary). The innovation seems to have slipped away and as a direct result we have multiple engines available to us now.
Ok now that I got my little side bar tangent out, which engine is right for you? I'm not going to make that decision for you, what is important (in Open BlueDragon team's eyes) is you have an option. We see that as possibly the most important part of being available, you have options. Each engine has compelling reasons to consider it for use. For me personally, in my development, I like the fact that I have complete control over the source code if I need/want it. I like that and that drives me towards OpenBD. For my company, we like a solid platform backed by a single entity and ColdFusion offers that to us.