While looking in Mariano's and David's blogs, I found very much useful tip's about the enhancements that the SP4 is carrying on the Extender module, mainly in "Scrolling Windows", "Multi currency", "Smart Lists" and "Notes".
Below link displays the complete list of enhancements on this module:
Mohammad R. Daoud
MVP, MCP, MCT, MCBMSP, MCTS, MCBMSS
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