prospero, I have been looking for C++ replacement for desktop programs non-stop for at least 5 years and found
nothing. Rubies, lisps and pythons are great in a little dark corner of server-side development where everything is under your control, but for targeting thousands of varying desktops you just can't take that route since many additional variables come into play: size of downloads, performance, startup times, windows compatibility, etc etc etc. Plus, all VM-based languages suffer from so-so integration into native OS or/and excessive weight. You can write an IDE or an Excel replacement in them, sure, but most desktop software tends to be much smaller.
My last C++ project was a background daemon that would download your RSS feeds and do some fancy parsing. I wish I could show you how much memory Java prototype has eaten vs C++ version processing the same OPML file.
No, C++ is not "essentially worthless" without Boost. In fact I never use all of Boost: your build times becomes #1 conversation topic in the office when you do. It's better to cherry-pick a few important and lightweight pieces (like pointers, any, functional, etc). Don't forget about HUGE selection of plain C libraries too.
Whatever C++ has been used for is still being written and re-written in C++ as we speak. Newer languages and paradigms wiped out the giant Visual Basic army of developers (yes, this is what people used to code "basecamps of the 90s" in, but I don't see these languages threaten C++/C/Obj-C domination for desktop software on Win/Linux/OSX.
In fact, how many native Python or Ruby GUI libraries are out there? I haven't heard of one. Only bindings to GTK/Qt.
With all that said, I will be the first to jump the wagon. If I ever get so lucky.