Is there any serial port facilities in Qt ?
If not, which crossplatform (desirable) libraries (for working with serial port and, maybe, with other I/O ports), do you recommend ?
Well, there's always Boost.
There is a great example about how to build a minicom-like application using Boost::Asio, that you can use to see if ASIO will attend your needs.
Since boost works on all platforms/compilers under the sun, the cross platform requirement can be checked.