Visual effects, to varying degrees are often negated from being a key component of usability. I can, for the most part, concede that to be the case. While well-designed effects can improve productivity by providing visual cues to what is going on, many only provide minimal benefits. Icons are not such a case, and that's why I think the Tango Project is more important than it might first seem.
Icons are one of the most basic components of a modern GUI and therefore are easy to overlook in terms of important features. For the most part, when we talk about icon themes today, it is in reference to eye candy themes that are more frivolous than practical. On the other hand, I believe the Tango Desktop Project is working on something more than just fluff.
What fascinates me about Tango's project? First, it aims to create a theme that will run on both GNOME and KDE by producing a common specification for icon names. This is a big step toward making it easy to produce icon themes for both desktops, but that can already be accomplished with a little work. The fascinating part of Tango goes deeper than that. Creating an icon theme that is intended to not only work on both desktops, but also to “feel at home” on both is a critical step forward.
Although the project features mostly GNOME veterans, including Tuomas “Tigert” Kuosmanen and Jakub “Jimmac” Steiner (whom OfB previously talked to in the Creative Penguin series), Steiner's blog entry about the new project lists numerous points of design where KDE's choices were opted for over GNOME's. This is what makes the Tango Project's icons so worthy of note; although GNOME-based themes such as Gorilla have appeared on KDE and KDE themes such as Crystal have appeared on GNOME, I know of no previous attempt to create a theme with the primary goal of being desktop neutral. (No, Bluecurve does not count.)
Why is this important? If a theme, or even themes, can be created that comfortably fit into both KDE and GNOME, an important milestone toward a unified desktop experience will have been achieved. A single set of icons across the desktop allows the user to find frequently used functions between applications without even a moment of hesitation.
Another exciting characteristic of this project is that it is forward looking. It considers not only making the icons fit in with KDE, but also Windows and Mac OS X. As Free Software applications such as the GIMP become increasingly of interest outside of the normal X11 desktop user base, providing an icon set that fits comfortably in other environments can only be a wise move.
Is Tango a magic wand that will eliminate all of the problems of the Linux desktop? Of course not. But, progress is made brick by brick, not wall by wall: Tango is surely worth a good number of bricks.