Several promo pics from the series finale were just released by FOX including an interesting Chloe one.
24: Chloe (Mary Lynn Rajskub) is faced with a difficult decision in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Kelsey McNeal/FOX
24: Jack (Kiefer Sutherland) readies for a dangerous move in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Ray Mickshaw/FOX
24: Jack (Kiefer Sutherland) contemplates his next move in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Kelsey McNeal/FOX
24: Jack (Kiefer Sutherland) readies for a dangerous move in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Ray Mickshaw/FOX
24: Jack (Kiefer Sutherland) readies for a dangerous move in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Kelsey McNeal/FOX
24: President Taylor (Cherry Jones, R) discusses the delicate international situation with Charles Logan (Gregory Itzin, L) in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Kelsey McNeal/FOX
24: Chloe (Mary Lynn Rajskub, L), Arlo (John Boyd, C) and Cole (Freddie Prinze Jr., R) work to save Jack’s life in the climactic two-hour 24 series finale episode “2:00-4:00 PM” airing Monday, May 24 (8:00-10:00 PM ET/PT) on FOX. ©2010 Fox Broadcasting Co. Cr: Kelsey McNeal/FOX
Update: Since a few have asked, according to the file names of the images, the Logan/Taylor pic, Chloe gun pic, and CTU group pic are from episode 24 while all the Jack Bauer ones take place in episode 23. And to get even more detailed on timeline – the Chloe gun photo had “Sc14” (which I assume stands for scene 14) in the filename while the CTU group pic (which mentions them working to “save Jack’s life”) was “Sc37”.