As anyone who's been around for 50 years would likely know (though I'm assuming here, as I'm not quite of that vintage myself), "L" is the Roman numeral for 50, as well as the last letter in "COBOL".
Which is only relevant for one reason: the day after the mainframe turned 45 years old, COBOL turned 50!
That's right: according to Wikipedia (see http://en.wikipedia.org/wiki/Cobol), COBOL had its genesis on April 8, 1959.
Now, I have to admit, this isn't actually one of the pieces of trivia that I normally cart around ready to spring on unsuspecting colleagues. Rather, I was made aware of it thanks to the following article: http://www.guardian.co.uk/technology/2009/apr/09/cobol-internet-programming.
This is a significant anniversary in the ongoing history of computing. And, coming four years after the 50th anniversary of SHARE and five years before the 50th anniversary of the IBM System/360 mainframe, it is part of a time line that sheds light on the nature of business computing. First, the definitive user organization for high-end business computing was formed, then the original business-oriented programming language was created (COBOL, after all, stands for COmmon Business-Oriented Language), and finally, the ultimate business computer was born.
But here's a connection that many people don't seem to have caught. Having written both COBOL and IBM Mainframe Assembler, it is my observation that the two languages are like twins. It's like the same business principles that led to the creation of COBOL were also key factors in the creation of the System/360 architecture, and were expressed in how both handled data and processing.
Of course, COBOL and the Mainframe have been inseparable since the beginning, and while many other great languages have since been introduced to make the mainframe even easier to program (for example, CA Gen and CA Easytrieve®), there continue to be billions of lines of tried-and-proven COBOL keeping the world economy running (and great products such as CA InterTestTM to keep the COBOL running).
So, here's to the real meaning of "Legacy" (i.e. "it works") and a half century of business-quality functionality: Happy 50th Birthday, COBOL!