The last two years have seen the KDE desktop not only rewritten from scratch, but adding innovation after innovation. Sooner or later, the moment had to come when its breakneck pace of development slowed -- and, judging from the second beta, that moment is the upcoming 4.5 release.
Not that KDE 4.5 is short of changes. However, most of them are either concerned with stability and appearance, or minor enhancements. By contrast, new applications or directions are few. You might call the 4.5 release a consolidation and refinement of the improvements made in previous releases in the KDE 4 series.
Officially numbered as 4.4.85, the second 4.5 beta can be compiled from source. Alternatively, you can scroll down the announcement page to find links to instructions about how to install packages for Fedora, openSUSE, and Ubuntu. These packages seem stable enough for the general desktop, but you might have crashes and segmentation faults with some of the minor packages.
KDE 4.5 has a few new applications, such as a Bookmark widget and a new Mah Jongg game -- not the tile-matching version normally found on computers, but the gin rummy-like game played in Asia. For the most part, though, those looking for new applications are apt to be disappointed.
The truth is, many of the changes planned for KDE 4.5 are minor. Not that they are unwelcome, but, unless you use a particular application regularly, you might easily miss them. That is especially true of changes intended to increase stability (after all, how do users know when an application is more stable? Only after they use it for a time and no crash occurs). Yet the cosmetic changes and small improvements are almost as easy to miss.
For instance, tabs in Konsole now have a context menu, from which you can detach, rename, or close a tab. None of this functionality is new, but in KDE 4.4, it was spread out over the File, Edit, and View menus at the top of the window -- as far away from the tabs on the bottom as you could get. Now, in 4.5, the functions are consolidated and easier to find.
Equally easy to overlook are improvements like the drag and drop support for tabs in the Dolphin file manager, the use of the semantic desktop features in creating Konqueror bookmarks, or the support in Kontact for alternate calendars and new holiday listings.
Admittedly, in places, the changes may add up. In particular, over two dozen changes are planned for Marble, KDE's answer to Google Maps and Google Earth . These changes include bookmarks, and the ability to update via OpenStreet Nominatim. Although all of them do not appear to be implemented in the second beta, enough are present to create a general sense that Marble is running more smoothly -- but it is hard to pinpoint exactly why.
The same is true of many of KDE 4.5's changes, especially if you are used to a particular work flow. Unless you regularly explore the interface, or stumble across changes by accident, you might never notice what is different. At the most, you might have a general sense that some KDE applications are running faster or have become more efficient or convenient. KDE 4.5 is one version in which you will want to read the release notes carefully, to see what changes might affect the applications you use the most.
The two places where KDE 4.5's changes are most noticeable are the notification tray and the System Settings Dialog window. In both cases, little or no functionality has been added, but considerable thought has gone into rearranging existing functionality to make it easier to use.
At a time when some desktops seem determined to send so many notifications that you never get any work done, for me one of the most welcome features in the KDE 4 series has been the ability to control the notices that display.
You can either broadly set the types of notices that you want to see, or set them never to display unless you specifically open them. If you are of the opposite opinion about notifications, you can also have them stay visible permanently rather than displaying for a few seconds then closing.
Now, in the 4.5 second beta, this control has been enhanced by an improved set of controls. Some of these improvements are simply cosmetic, but there are also one or two that improve user control over notifications.