Learning Object Tools

A reader from another country has asked me about Learning Object Tools. I asked him to clarify what they meant and the response was:

Learning Object Tools are those that allow you to create, edit and manage learning objects.

There is also a bit of language barrier. I pointed them at the Wikipedia article - Learning Object. It cites quite a few repositories and briefly mentions "Burrokeet is an Open Source Software tool that assists in the creation of Learning Objects from existing content. " This is something I'm not familiar with. I also suggested looking at LCMS products. And looking at SCORM / SCOs.

But it got me to thinking that I've really not looked at Learning Objects in quite a while - and I've not really kept up on Learning Object Tools.

So, I was hoping that someone could help me and him:

1. What are good general discussions of learning objects and learning object tools?
2. My impression is that these were a big topic about 4-5 years ago, and a lot is happening in academia, but not much is happening in corporate spaces. Is that the right impressions?
3. What are the categories of tools that represent this space?
4. What are some specific tools within those categories?
   

Any help would be appreciated.