What is the most popular developing environment between Java, PHP or C, but also Delphi and other Objective C ? If you wonder what next language to use for your development, I suggest to read that excellent report ( updated May 2010 ):
http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html
Nice graph and stats, to check the trends of users of Delphi ( I have a one-day event with Embarcadero tomorrow so I was looking at the market share for it ), or Objective-C which is used for iPhone and iPad developments.