Speaking of shakeout and convergence: I don't see any reason why Mapbuilder and OpenLayers, the two leading open source AJAX map libraries, need merge. Choice is good, and these projects offer distinctly different approaches. Mapbuilder is closely tied to GeoServer, highly structured, and disciplined. It's a natural fit for Java projects. OpenLayers, on the other hand, is simpler, XSLT-free, and more attractive to Python, Ruby, and PHP (if you must) users.