There isn't a whole lot of PLD-related stuff on the Web yet. Here are a few links presented in no particular order.
By and large, if you're interested in PLD and want the latest news your best bet would be Medline on the Web, the best of which (in my opinion) is PubMed, coming to you courtesy of the NCBI.
Dr. Larry Daniel has edited a special issue of Biochimica et Biophysica Acta (a.k.a. BBA) that is dedicated to phospholipase D. Most aspects relating to phospholipase D structure, regulation and function in eukaryotic cells (including yeast and plants) are covered by many of the prominent figures in the field. Click for the Table of Contents of PLD in BBA.
Dr. David Lambeth has posted a beautifully illustrated overview of phospholipase D in mammalian cells. The Phospholipase D Page provides information on the coordinate activation of PLD with other lipid signaling pathways and discusses its regulation by cytosolic factors, including small GTPases, PKC, and a 50 kDa protein.
A general overview of the PLD field can be found in a special issue of Chemistry and Physics of Lipids edited by V. Natarajan, and devoted in its entirety to PLD. Although published nearly four years ago this issue is still a valuable resource and includes reviews on PLD in neutrophils, platelets and megakaryocytes, the regulation of PLD by ADP ribosylation factor, protein kinase C and tyrosine kinases, the activation of PLD by sphingoid bases, the in vitro enzymology of PLD, and the signaling role of PA and PA phosphohydrolase. (Table of Contents)
The Bioinformatics Group of ISREC (Swiss Institute for Experimental Cancer Research) in Epalinges s/Lausanne, has posted a page describing the PLD domain, found in all cloned eukaryotic PLDs, some prokaryotic PLDs and a few phosphatidyltransferases. The page contains a profile of the PLD domain that can be used for database searches.
More links will (hopefully) follow soon.