You can dowload the source code and binaries from the official Qt Project CDN. The tarballs for building on Unix systems like Linux are in the split_sources subdir — Linux distribution packagers will want to use them. Once those packages exist for distributions, they will be listed in the Qt 5 unofficial builds page.
This is the first Qt 5 release to also include installable binaries. Windows and Mac users have had them for ages in Qt 4, and Linux users have enjoyed them in the past in the form of the Qt SDK binary installers. As far as I can remember, this is the first pure Qt library release to contain Linux installers.
But, as the nature of the beast goes, those installers are known to work only on Ubuntu distributions. The main reason for that is because Qt 5 depends on the ICU libraries, whose developers went to the “OpenSSL School of Releasing” (along with the Boost developers) and haven’t learned yet to make binary-compatible releases. Sorry about that. If you don’t have the build capacity to compile the sources yourself, you may want to wait until packaged, binary builds show up for your distribution (in the form of RPMs and DEBs).
The goal of the beta, as I explained in a previous blog post release is to gather feedback on the implementation and to get bug reports. From this point on, the Qt 5 API is “soft-frozen”, meaning that it will not change incompatibly any more, except to fix major issues that we encounter or we’re told about in the form of feedback. If that happens, we’ll make sure to make a note of it in the release notes.
That means that Qt 5.0 beta1 is a suitable starting point for porting applications and writing new code. Your work will not be wasted. But you might run into bugs, so please report them to us, in the Qt Project Task Tracker. We’re also very interested in bugs related to packaging, building, the installers, documentation, etc. Just be sure to look first at the Known Issues page before reporting anything.