I think "most popular" depends partially on the area being considered.
For client-side Internet programming, most people are tending to be using some bastard-ized combination of JavaScript, VBScript (if for IE only, really), Shockwave (mainly for games), and Java.
For server-side web programs, most are written as scripts, and are written in: PHP, Perl, ASP in JavaScript or VBScript, and I'm sure there's some usage of the rarer scripting languages, ie Python and the ilk. In addition, programs can be written in pretty much any language that can output straight text... commonly C or C++, but I also know a friend a few years back who did all the web page generation in a Visual Basic application.
For more desktop apps, the field is a bit more varied. Although I have seen some programs developed in Java, by and large development is done via one of two routes: C/C++ or RAD (either VB or Delphi, Windows applications ONLY). C/C++ is by and large the first choice for anything speed intensive, although a front end for any C/C++ DLL or COM component can certainly be written in VB.
With the current popularity of COM on the Windows platform, most people I know are using C++ with ATL (Active Template Library) to develop very small and fast COM objects, which can then be hosted in any other application.
If you're looking to develop on other platforms, C/C++ seems to be the first choice for most programmers, which one being dependent on the availability of compilers, libraries, etc. Linux development seems predominantly in C, particularly low level work, with some C++. Mac development I have no clue about, although I'd hazard a guess that it's C/C++ as well.
All of this changes if you have to bring in legacy code. The moment a legacy app is brought into the picture, the landscape changes. (And good luck!)
This is just in my experience, obviously.