First of all scholars haven't yet found out which day Shakespeare was actually born on. Second, England was on the Julian calendar until 1752. You can get a lot of Shakespeare's birthdays if you like. The Folger Shakespeare Library's Birthday bash was yesterday (see metro section in today's Washingtton Post). I went to it once, and was greatly disappointed. All PR types and entertainers and audience; the librarians and the readers (those actually knew something about Shakespeare) didn't come.
Hey the doxie over the dell!