If you feel that C-like pre-processor directives are really second nature to just about everybody who uses Perl, then you could try "=ifdefined" -- this wouldn't be any worse that "=begin"
Well, I admit being inspired by C preprocessor's directives. Ideally, I would like to use the =if, =ifdef, =elseif and =else and =endif family. However, any of these will cause severe noise with even the standard pod2html and pod2man utilities. And worse, it will include them inside the generated documentation!
Maybe I should call the pragma "ifdef" and support all of the above pod markers and include =begin and =end (good point "Mr. Muskrat") as synonyms that can be used in the current code base without upsetting current pod parsers?