I generally like to play with new versions of software, but had not got around to looking at the latest version of KDE. Version 3 has been slowly evolving for a while, but this is quite different. It adds some new features such as 'widgets' that you can rotate, but I'm not sure why you would. I installed it and was given the choice when logging in as to which version I wanted to use. KDE4 seemed to ignore my settings for what applications run at startup. I also had to configure the new Kopete. The K menu is different. You have to click through different levels to get to most applications. It certainly looks like it could offer some nice visual tricks, but I'm not sure how they would benefit me. I generally run things like my browser in full screen mode and so rarely see the desktop. or any widgets that may lurk there. V4.1 is due fairly soon. Maybe that will make it more usable and I can try it again then.
One feature I like to use on KDE/Linux and on Windows is to have applications that minimise to the tool tray. This is especially useful for things like email and instant messaging clients as I will generally only look at them when something happens, like receiving a message. I may sometimes open an IM window just to see who is on-line. Then it is very useful if I can click the same icon in the tray again to make the window close. None of the Windows seem to do that, but the Linux ones generally do. Unfortunately they are a little inconsistent in their behaviour.
If I click the tray icon when the window is either closed or hidden then I expect it to come to the front. Kmail closes if the window is open and hidden, but other KDE apps behave as above e.g. Amarok and Konversation. I think that consistency is very important and hope that the KDE teams are looking at this sort of thing.
The other new thing I've been playing with is Firefox version 3. This was included in Ubuntu 8.04, even though it is still a beta. The main obvious new feature is that the address bar is more intelligent. I often used the history to start typing a URL to go to a page I often visit, but now you can type any part of the page title to get it back. If you click to show recent history it does not show as many pages as it used to. I miss that as I would often use that list to look check back at recent pages I had visited. Unfortunately this version is less stable than version 2. It frequently crashes when I am entering text on pages. This happens most often on Twitter. I'm still having fun with Twitter. It is more intimate than blogging and I have had a few exchanges with strangers that would not have happened otherwise. So if you are not already Twittering, why not?