What's a "prepared speech?"

The format varies slightly from club to club, but the basics include:

the business meeting (usually very brief)
introduction of the Toastmaster of the Meeting, who presides over the program that day and explains the meeting as it goes along
prepared speeches from members (of which more below)
impromptu speeches from members (also known as Table Topics, of which more below)
oral evaluations of the prepared speeches (of which more below)
reports from other evaluation personnel, such as speech timer, grammarian, "ah" counter, wordmaster, and General Evaluator.

Meetings last anywhere from one hour (especially at lunch or breakfast) to three hours (if the club meets infrequently or has long-winded speakers).

Portland Toastmasters (Club 31) limits the meeting to two hours (6:15pm to ~8:15pm) but usually lasts approximately one and a half hours.