Start konsole with the following switch --real-transparency, ie konsole --real-transparency and select a transparent theme. You will also need a compositing manager such as compiz though.

If you have a card which supports compositing natively (e.g. nvidia) you can enable simple transparency in KDE windows from its own settings - without the need of compiz and the like.

how, if I enable translucency or special effect I simply get fake transparency?

Visit the following link. It might be helpful.
http://www.brunolinux.com/02-The_Terminal/...nt_Console.html

Indeed. kcontrol/Desktop/window behavior/Translucency/...
But you need either a card which supports compositing natively (nvidia), or a soft compositing manager.
The effects are way less impressive than the ones made by compiz(fusion), but the window management remains the old, good KDE one, not the shitty things compiz is doing.

Compiz runs pretty stable here with my nvidia 6600gt. Anyway using kwin you can make an entire window transparent, the --real-tyys ransparency switch only makes the background transparent while the rest stays legible...