From Jayski.com:

Testing at Las Vegas - Jan 30/31-Feb 1: Las Vegas Motor Speedway has received 41 entries for NASCAR Preseason Thunder Las Vegas. This test session, which many NASCAR drivers are calling the most important of the season, will take place Jan. 30, 31 and Feb. 1. Each team will be allowed to test for two of the three days. The public is invited to watch the test sessions free of charge each day from 9 a.m. to 5 p.m.

Here is a tentative list of test dates and drivers:
Jan. 30-31: #07-Clint Bowyer, #31-Jeff Burton, #8-Dale Earnhardt Jr., #7-Robby Gordon, #66-Jeff Green, #29-Kevin Harvick, #88-Dale Jarrett, #32-Travis Kvapil, #6-Mark Martin, #26-Jamie McMurray, #38-Elliott Sadler, #00-Hermie Sadler, #21-Ken Schrader, #49-Brent Sherman, #41-Reed Sorenson, #40-David Stremme, #1-Martin Truex Jr., #55-Michael Waltrip and #4-Scott Wimmer.
Jan. 31-Feb. 1: #16-Greg Biffle, #22-Dave Blaney, #2-Kurt Busch, #5-Kyle Busch, #99-Carl Edwards, #24-Jeff Gordon, #48-Jimmie Johnson, #9-Kasey Kahne, #17-Matt Kenseth, #43-Bobby Labonte, #96-Terry Labonte, #14-Sterling Marlin, #19-Jeremy Mayfield, #42-Casey Mears, #01-Joe Nemechek, #12-Ryan Newman, #45-Kyle Petty, #10-Scott Riggs and #25-Brian Vickers.
Jan. 30 and Feb. 1: #11-Denny Hamlin, #20-Tony Stewart and #18-J.J. Yeley