For most people, a birthday is a once-a-year celebration of, well, them, and that's that. Sure, there are your stereotypical birthday parties with the funny hats and noisemakers and cakes and clowns, but it still remains one day among 365, guaranteed to occur each year so long as there is no Gregorian calendar overhaul.
It's a little different when you're born on February 29th—or, as it is otherwise known, Leap Day. That the day only occurs once every four years isn't just amusement; it can be cause for considerable confusion: when do you celebrate a birthday on a non-leap year? How does that affect age-dependent things such as driving licenses and drinking ages? Answer: it actually varies by country.
Leap day, in a sense, feels like a kind of baseball twilight zone—caught in between the camp drills of February and the actual exhibition games of the next month. Indeed, the first exhibition games of the season are often intra-squad or against university teams; hardly the affairs of late March, where the game resembles something more reminiscent of what one will see in April.
It probably won't come as a surprise that out of the thousands of major-league baseball players only eleven share the February 29th birthdate. The very first major-league player to be born on February 29th was Dickie Pearce (in 1836—and if you want to know how long ago that was, that was a year before Victoria ascended the English throne, it was the year Martin Van Buren was elected president*, and it was the year the Wisconsin territory was created); he played for such stalwarts as the New York Mutuals, Brooklyn Atlantics and St. Louis Brown Stockings.
The most recent major leaguer to be born on leap day is journeyman outfielder Terrence Long, who ended his eight-year career with the Yankees in 2006. Steve Mingori had a 10-year pitching career for Cleveland and Kansas City, though WAR suggests he spent most of the time treading water. Al Rosen, the winner of the 1953 AL MVP is probably the most well-known of all the leap day baseball babies (and with a .422 OBP, .336 average, and 43 home runs, clearly an MVP well-deserved), while Pepper Martin, a four time All-Star, had the longest career—13 seasons (including three missed years during World War II), all with the St. Louis Cardinals.
There are other, important baseball-related events to have occurred on leap day; they include an assertion by Ban Johnson that the Western League should be treated as something more than a minor league—indeed, it was the direct precursor to the American League, and, more recently, Hank Aaron becoming the first ballplayer to sign a $200,000 contract, and a ruling that Barry Bonds' testimony in the BALCO case should be made public.
Since February 29th only comes around once every four years, chances of seeing a leap day baby become a Hall of Fame member are low—even among current major leaguers who give their birthdays as February 28th or March 1st the pickings are somewhat slim**—but there's always a chance that of all the future baseball stars born on this day, who will make their debuts sometime between 2032-2040, one among them will be good enough for a berth in Cooperstown...
*leap years are always election years, and, more recently, Summer Olympics years.
**One could here perhaps throw in a not-quite-G-rated joke about Aroldis Chapman's 104 mph fastball and his too-soon arrival...