Part1:

http://marclognoul.eweb703.discountasp.net/itblog-en/post/2009/05/13/SharePoint-People-Picker-and-Active-Directory-Part-1.aspx

http://blogs.msdn.com/b/rajank/archive/2009/09/01/all-you-want-to-know-about-people-picker-in-sharepoint-functionality-configuration-troubleshooting-part-1.aspx

Part 2:

http://marclognoul.eweb703.discountasp.net/itblog-en/post/2009/07/24/SharePoint-People-Picker-and-Active-Directory-Part-2.aspx

http://blogs.msdn.com/b/rajank/archive/2009/09/20/all-you-want-to-know-about-people-picker-in-sharepoint-functionality-configuration-troubleshooting-part-2.aspx

troubleshooting article (sharepoint wss v3 people picker issue): http://www.petri.co.il/forums/showthread.php?t=43263

troubleshooting

article (people picker browse UI – protocols): http://msdn.microsoft.com/en-us/library/dd357076(PROT.13).aspx