Quick post of how-to get Citrix Receiver up and running on a Ubuntu 11.04 the installation is the same for 12.04.
First of go to Citrix Receiver download site and choose Linux on the “For desktops”
http://www.citrix.com/English/ss/downloads/details.asp?downloadId=2323812&productId=1689163
From here you choose the .deb file. (This is part of the debian software package format ) 
Choose to open it via Ubuntu Software Center and press OK.
From here just click the install button.
You will get a pop up which ask if you wish to accept the EULA, click Yes and press Forward.
After it is done installing, you can find it via the search function.
But before we can start it we have to do some changes, by default the Icaclient has it’s own cert-store. And it only ships with 4 – 5 certs so most likely, when you setup a connection to en SSL encrypted site you will get an error message.
So therefore we need to copy CA-certs from Firefox CA-store into the ICAclients store.
From terminal run the command,
sudo cp /usr/share/ca-certificates/mozilla/* /opt/Citrix/ICAClient/keystore/cacerts/
After you have run the command you can now start the client.
The GUI is… well terrible..
Click the View button and choose Xenapp 
Enter the URL of your WI
Enter your username and password
Now the clients list all my available apps just like the regular Citrix client does.
And I can start connections like a regular client.
AND! just ignore the fact that I have 405 updates available via my update manager 
/bad /bad IT admin.