Tapia v. Gonzales, 430 F.3d 997 (9th Cir. Dec. 6, 2005) (being turned away at the border by immigration officials does not have the same effect as an administrative voluntary departure and does not itself interrupt the accrual of an aliens continuous physical presence for purposes of cancellation of removal).
http://caselaw.lp.findlaw.com/data2/circs/9th/0374615p.pdf