Update: The eighth season of 24 is arriving on Netflix February 12, 2011. More details here.
Starting on April 1st, 24 Seasons 1 through 7 will be available to stream through Netflix’s Instant Watch service (but apparently not the 24: Redemption TV movie). UPDATE: 24: Redemption is also there, but listed as the first episode of 24 Season 7.
You can add them to your Netflix queue now: