Hi Emy,
You seem to confuse something. CALF is a suite of plugins. LADSPA is a plugin standard.
So you have some CALF plugins which are LADSPA plugins. You also have some CALF plugins which are DSSI plugins (another standard for soft synths or "instrument" plugins). And you have some CALF plugins which are LV2 plugins (another standard which can deal with effects and instruments. However, you don't have any LV2 host in ubuntu karmic official repos, so you might want to compile ardour from source, or get a .deb with LV2 support, or wait a bit and upgrade to lucid whose ardour will have LV2 support, or ... or ... (put more possibilities here but take it easy anyway)).
Then you have "stand-alone" effects and soft synths, which are jack clients so you can connect them to any other jack client (for example, as an insert in ardour). Then you have wrappers for Windows VST and VSTi (you need wine for this), for example the so-called "dssi-vst" (which is also a ladspa-vst wrapper and it also provides a simple, stand-alone vst host jack client).
Take a look at this:
http://lievenmoors.github.com/plugins.html
Installing CALF plugins in ubuntu is easy. Search and install in synaptic or do a "sudo apt-get install calf-plugins". This will install CALF LADSPA, CALF DSSI and CALF LV2 plugins. There are other excellent plugins which are not in the ubuntu repos but you can compile from source and/or install the binaries from their websites.
I wrote an introduction to LV2, in Spanish (I am Pablo_F in hispasonic if you are emy_knopfler there):
http://semicorchux.blogspot.com/2010/01 ... tos-y.html
HTH, Pablo