DC Comics has referenced the number 52 on several occassions.
52 the comic
52 versions of earth
the New 52
etc.
Is there some numerology working here? Is there a code behind it?
There are 52 weeks in a year, and comics are published weekly. Post-Infinite Crisis, all the titles jumped forward a year, this event was referred to at the time as One Year Later. The events of that missing year were revealed by the weekly series 52. It was published weekly and had 52 issues, so it was published over one year of real time, and it covered one year of time in universe as well.
The big reveal at the end of 52 was what the number referred to in universe. The events of Infinite Crisis did not just create New Earth. It created 52 parallel universes, with New Earth being in one of them.
The New 52 is the name DC's given to the universe-wide reboot that started September 2011. The number in this case refers to the number of comics they'll be publishing over the course of the month. All of the books are reset to issue number one.
The initial picking of the number comes from the number of weeks in a year, which is the number of weeks of comics they publish in a year. After 52, it's come to have a meaningful use in universe, along with positive connotation to comic fans who enjoyed 52.
After the events of Infinite Crisis, the main titles skipped a year forward. The series 52 was setup to be a weekly series that detailed what happened during that missing year.
Since that series was so popular, that's what led them to continue the 52 motif in the new relaunches.
There ARE 52 weeks in a year, and I believe DC does try to have new issues of something out every week.
It could be as simple as that.
DC Comics started with Batman and Superman and produced an issue every month. But as years have gone by with more characters being invented, some from the original two are considerable* that sometime in the nineties it was possible to release a new comic book issue every single week. 52 weeks a year, 52 comic books issued every year. Its become more than an obvious shout out when DC creates comic book stories such as the 52 and with the newest reboot being called the New 52.
(*For example, Superman = Supergirl, Superboy, Lois Lane, team ups as well as numerous reboots and teamups,etc.
Christopher Reeves (Actor who played Superman) died at age 52 :S