According to my research, the next generation X3 (which will built in SC, USA) will be the MY2010 edition, which starts production in 2009.
Even though this article is mainly about the F3, it includes information about the next X3:
http://www.bmwcca.org/node/8307
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2007 E92 328i 6MT-Space Gray/Black Dakota/Gray Poplar w/heated seats-PCD 4/27/07 (SOLD)
2009 E90 328i xDrive 6AT-Space Gray/Oyster Dakota/Dark Burl Walnut w/ZPP,ZCW,Xenons-ED 4/17/09 - Redelivery 5/30/09 (SOLD)
2014 E84 xDrive28i 8AT-Alpine White/Black Nevada/Silver Matte w/ZMV,ZLP,494 - DD 3/14/14 (SOLD)