On Fedora Linux, most gstreamer plugins are available in packages whose names start with gstreamer-plugins-. You can use yum to search for matching packages available to install. For example, if you want to install the schroedinger plugin:

# yum search schroedinger
Loaded plugins: refresh-packagekit
============================ Matched: schroedinger =============================
gstreamer-plugins-schroedinger.i386 : GStreamer Plugins that implement Dirac
                                    : video encoding and decoding
schroedinger.i386 : Portable libraries for the high quality Dirac video codec
schroedinger-devel.i386 : Development files for schrodinger
        
        

If it is available, you can install it (as root):

#  yum install -y gstreamer-plugins-schroedinger
Loaded plugins: refresh-packagekit
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package gstreamer-plugins-schroedinger.i386 0:1.0.3-2.fc9 set to be updated
--> Processing Dependency: libschroedinger-1.0.so.0 for package: 
gstreamer-plugins-schroedinger
--> Running transaction check
---> Package schroedinger.i386 0:1.0.3-2.fc9 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
 Package                 Arch       Version          Repository        Size 
=============================================================================
Installing:
 gstreamer-plugins-schroedinger  i386       1.0.3-2.fc9      updates   40 k
Installing for dependencies:
 schroedinger            i386       1.0.3-2.fc9      updates           211 k

Transaction Summary
=============================================================================
Install      2 Package(s)         
Update       0 Package(s)         
Remove       0 Package(s)         

Total download size: 250 k
Downloading Packages:
(1/2): gstreamer-plugins-schroedinger-1.0.3-2.fc9.i386.r |  40 kB     00:00     
(2/2): schroedinger-1.0.3-2.fc9.i386.rpm                 | 211 kB     00:00     
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing     : schroedinger                                      [1/2] 
  Installing     : gstreamer-plugins-schroedinger                    [2/2] 

Installed: gstreamer-plugins-schroedinger.i386 0:1.0.3-2.fc9
Dependency Installed: schroedinger.i386 0:1.0.3-2.fc9
Complete!
        
        

On Ubuntu Linux, most GStreamer plugins are available in packages whose names start with gstreamer0.10-plugins-. You can use the Synaptic Package Manager to search for matching packages available to install.

On the command-line you may also use apt and apt-search. For example, if you want to install the schroedinger plugin:

$ apt-cache search schroedinger
gstreamer0.10-schroedinger - GStreamer plugin for encoding/decoding of Dirac 
video streams
libschroedinger-1.0-0 - library for encoding/decoding of Dirac video streams
libschroedinger-dev - library for encoding/decoding of Dirac video streams 
(development files)
libschroedinger-doc - library for encoding/decoding of Dirac video streams 
(documentation)
oggconvert - Convert media files to free formats

        

If it is available, you can install it:

$ sudo apt-get install gstreamer0.10-schroedinger
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  python-kiwi librrd2 python-rrd flumotion-flashplayer cortado
Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:
  gstreamer0.10-schroedinger
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/35.4kB of archives.
After this operation, 160kB of additional disk space will be used.
Selecting previously deselected package gstreamer0.10-schroedinger.
(Reading database ... 367640 files and directories currently installed.)
Unpacking gstreamer0.10-schroedinger (from 
.../gstreamer0.10-schroedinger_1.0.1-2_i386.deb) ...
Setting up gstreamer0.10-schroedinger (1.0.1-2) ...