Automatic layout algorithm?

    I need to position a group of nodes that have a hierarchical relationship and any number of levels. Isnt there a mechanism for positioning all the nodes in a document based on a top level node?

You can use either GoLayoutTree or GoLayoutLayeredDigraph, depending on the kind of graph you expect to have.

Can you let me know which version has these api’s and is there a eval version to check out if this meets our requirements

GoLayoutTree is new for version 2.5. GoLayoutLayeredDigraph has been there forever.
Both of the GoDiagram Win and GoDiagram Web kits let you evaluate both of these features, as well as all of the other features that GoDiagram offers.
You can run the LayoutDemo sample application and some of the other samples in order to see what GoLayout can do. DataSetDemo, for example, uses GoLayoutTree. Flowgrammer and ObjectBrowser use GoLayoutLayeredDigraph automatically; other samples such as OrgCharter and ProtoApp and SubGraphApp also use GoLayoutLayeredDigraph, but only upon user command.
And you can modify and rebuild any of the samples or any program you create, in order to experiment with any of the features GoDiagram offers.