I can't shake off the feeling that in terms of core language features of C++0x, vNext is going to be a bit of a letdown. We've had more confirmations of stuff not going to be available than stuff that's actually going to be implemented, like explicitly defaulted and deleted special member functions and non-POD initializer lists. I just hope that additions like scoped enums (a basic feature of Java/C#) will make it. It's especially painful because GCC already does all of this.
With the advent of domain specific libaries such as <atomic> and <thread> I'd say Unicode operations and data types could very well be part of the standard. It is exactly those platform specific functions and types that drive people to higher level languages like Java, even if those are heavily dumbed down; they at least provide this cross-platform functionality with easy to use interfaces.
Of course, Qt could be an option but I despise it. It's not even a library, it's a complete application framework that takes over your programming environment with custom build-tools and tries to reinvent the STL.
Marek, exactly, just use the OpenSSL crypto library. It contains every hash algorithm anyone would ever want to use. They're all implemented using the same set of functions (init, update, finalize). You won't have to implement anything yourself to support buffered I/O. The documentation seems to be outdated so browse the source to see what's available (sha256 is in the sha dir).