Would you recommend Iron Ruby, Iron Python, or PowerShell for making a C# application a script host?
After some quick tinkering, right now I'm leaning towards powershell for two main reasons (note these a purely my opinions and if they are wrong, I'd love to know!!!):
1) It's simple to create a runspace with classes in your application; therefor it's easy to make your application scriptable. 
2) I've heard some rumors that IronRuby and IronPython are losing support from Microsoft, so they may be a poor long term solution?
As this is my first time adding scripting to an application though, I'd welcome all the advice I can get from people who have been down this road before.
Specifically, besides letting me know whether you agree with my two points above, I'd like to know if IronRuby and IronPython are much easier to use (for a user, not developer) than powershell, and if in your experience using the DLR is as easy as just passing an object to a powershell runspace? And if I added support for the DLR and IR/IP scripting would my application still be backwards compatible with XP?
number 2 is true (the dynamic lang teams have been losing headcount for awhile now) and an excellent reason.  Ruby and Python aren't MS languages, and as such Iron * is just 'get it working on .NET'.  PowerShell is a Microsoft creation, Microsoft-controlled, and Microsoft-supported.
More importantly, multiple Microsoft products have taken deep dependencies on PowerShell (Exchange, SharePoint, etc.) so there's very little question of PowerShell's ongoing support as a language.
Last, PowerShell considers being the scripting lang for other applications as one of its first-class support targets.
Would you recommend Iron Ruby, Iron Python, or PowerShell for making a C# application a script host?