This is an interesting post by Marc Andreessen. He describes what he considers the three types of platforms companies build on the Internet. Worth reading to the end, even though it’s quite long.

If I had gotten my way, ESPN.com would’ve joined the level 2 platforms on the Internet. There are few reasons to not do it, and Andreessen’s point about AOL is absolutely right on target. Imagine the Internet if AOL had actually moved in that direction?

I don’t agree with everything he’s saying, and there is the obligatory Ning plug toward the end, but the broad point is absolutely right. The question is which businesses will thrive with that kind of platform approach, and whether level 3 makes sense for those businesses. There are a number of businesses where APIs beyond Level 1 don’t make sense.

Or, to put it another way, is there room for an open source version of FBML or FBJS to enable the plugin development of what he calls Level 2?