(Updated Feb 18) Note: These data actually relate to a gathering of Twitter users in Iran, not Egypt. Apologies for the error, and thanks to the commenters for the correction.
Twitter played a significant role in the recent uprising in Egypt, with protesters communicating via tweets marked with the #25bahman hastag (February 14 in the arabic calendar) to plan and rally for the demonstration. Michael Bommarito downloaded all such tweets and plotted their frequency over time using R's ggplot2 library:
Not surprisingly, the activity peaked on February 14. The complete set of tweets would be an interesting focus for further analysis; they can be downloaded from Bommarito's post linked below.
Update Feb 18: As commenters have pointed out, the #25bahman hashtag
Michael Bommarito: Dataset: 5 Days of #25bahman