Macro/Scripting language for non-developers with a simple GUI-based editor

Question

We wish to provide people to be able to add some logic to their accounts(say, given a few arguments, how to compute a particular result). So, essentially, this would be tantamount to writing simple business rules with support for conditionals and expressions. However, the challenge is to provide them a simple online editor where they can create the logic (preferably) by completely visual means (drag/drop Expr-tree nodes maybe -- kinda like Y! pipes).

Does anybody know of a scripting/macro/domain-specific language that lets people do this? The challenge is the visual editor, since we don't wish to invest in developing the UI to do the editing. The basic requirements would be:
1. Embedded into another language, or run securely (no reboot -n or <JUNK-DANGEROUS-COMMAND> >> ~/.bashrc)
2. Easily accessible to users without coding background (no need of any advanced features)
3. Preferably have a simple GUI based editor to create the logic programs accessible to non-developers (kinda like spreadsheets)
4. Some ability to generate compile-time warnings (invalid code) would be good (Type safety?)
5. Ability to embed some data before execution which is available to the interpreter (Eg., name, birthday, amount)

Anybody tried doing something like this and got any ideas? I looked at Lua, Io, Python, Ruby and a host of others, but the challenge essentially is that I don't think non-programmers will be able to understand the code all that much. Something that could be added via "meta-programming" to say a Ruby would be good as well, if an editor could be easily developed!

Answer 1

As a matter fact, Microsoft is developing Oslo, which is right up your alley. Chris Sells has been writing a lot about it recently.

It is designed to be a way to author DSLs and also to visually author these models with a graphical tool called Quadrant. Sounds very very similar to what you are looking for.

Open source wise, Ruby I think can be close, as you can see if you look at _whytheluckystiff's Try Ruby or Hackety.