Although Span hit seven triples in 2008, tied (with Jacoby Ellsbury) for the AL lead with 10 last year, and now has seven in 2010, he had never before hit more than one in a game.
(Curtis Granderson had 23 triples in 2007. Wow! That was the most in a season since Cleveland's Dale Mitchell had 23 in 1949. The last person to hit more than 23 was Kiki Cuyler, 26 for the 1925 Pirates.)
In the B-Ref era (1920-39, 1952-now), Span is the 29th player with three three-baggers in one game. Baseball Almanac has a more complete list.
Dave Brain did it twice in one season -- 1905 -- for two different teams: on May 29 for the Cardinals and on August 8 for the Pirates.
The record for triples in a game is four:
George Strief, Philadelphia Athletics (AA), June 25, 1885Span tripled in the 1st, 4th, and 5th innings. He also singled in the 3rd and walked in the 7th.
Bill Joyce, New York Giants (NL), May 18, 1897
Also, on this date in 1934, Lou Gehrig hit three triples against the Senators, but the game was rained out after 4½ innings and everything was wiped from the books. (Biscuit Pants hit two triples in a game three times.)