#Clojure - 44 71 chars

(defn rs[s](reverse(re-seq #"\S.+?[.!?]"s)))

Improved and simplified RE, eliminated unnecessary whitespace.

Output is a sequence of the sentences in the original string, with the order of the sentences reversed:

Input: "Hello friend. What are you doing? I bet it is something I want to do too!" Output: ("I bet it is something I want to do too!" "What are you doing?" "Hello friend.")

Clojure - 44 71 chars

(defn rs[s](reverse(re-seq #"\S.+?[.!?]"s)))

Improved and simplified RE, eliminated unnecessary whitespace.

Output is a sequence of the sentences in the original string, with the order of the sentences reversed:

Input: "Hello friend. What are you doing? I bet it is something I want to do too!" Output: ("I bet it is something I want to do too!" "What are you doing?" "Hello friend.")

#Clojure - 71 chars

(defn rs [s] (reverse (map first (re-seq #"(\S.+?[.!?])(?=\s+|$)" s))))

#Clojure - 44 71 chars

(defn rs[s](reverse(re-seq #"\S.+?[.!?]"s)))

Improved and simplified RE, eliminated unnecessary whitespace.

Output is a sequence of the sentences in the original string, with the order of the sentences reversed:

Input: "Hello friend. What are you doing? I bet it is something I want to do too!" Output: ("I bet it is something I want to do too!" "What are you doing?" "Hello friend.")