JavaFX isn't available for Linux and OpenSolaris yet. As to why, I suggest you read Josh Marinacci's blog: A Word on Linux and Solaris Support. However, this hasn't stopped the community from documenting how to install JavaFX on Linux. And not surprisingly, those instructions work very well for OpenSolaris. With some minor adjustments, here are the exact steps I to took to get the JavaFX SDK running in NetBeans on OpenSolaris.

Step 1. Install NetBeans

The NetBeans IDE makes working with the JavaFX SDK much more enjoyable. You'll need NetBeans 6.5, if you don't already have it installed:

bleonard@opensolaris:~$ pfexec pkg install netbeans

PHASE                                          ITEMS
Indexing Packages                            554/554 
DOWNLOAD                                    PKGS       FILES     XFER (MB)
Completed                                  22/22   5931/5931 204.40/204.40 

PHASE                                        ACTIONS
Install Phase                              7387/7387 
Reading Existing Index                           9/9 
Indexing Packages                              22/22 

Step 2. Downoad the NetBeans JavaFX Plugins

The JavaFX Plugins can be found here: http://updates.netbeans.org/netbeans/updates/6.5/uc/final/stable/modules/javafx/. We'll use wget to download them:

bleonard@opensolaris:~$ mkdir javafxnbms
bleonard@opensolaris:~$ cd javafxnbms
bleonard@opensolaris:~/javafxnbms$ wget -r -l1 -np -nH --cut-dirs=9 -A.nbm http://updates.netbeans.org/netbeans/updates/6.5/uc/final/stable/modules/javafx
--12:02:12--  http://updates.netbeans.org/netbeans/updates/6.5/uc/final/stable/modules/javafx
           => `javafx'
Resolving updates.netbeans.org... 72.5.124.114
...

FINISHED --12:05:10--
Downloaded: 68,475,450 bytes in 25 files 

Step 3: Install the JavaFX Plugins

1. Start NetBeans and select Plugins from the Tools menu.
2. Select the Downloaded tab and click the Add Plugins... button
3. Browse to the javafxnbms directory, select all of the plugins and click OK.
4. Uncheck the JavaFX Weather Sample, JavaFX 1.0 and JavaFX Source Debug plugins.  These plugins are leftovers from the Preview SDK and will fail to install. Your Plugins dialog should look as follows (click to zoom):
   
   
   
   
5. Install the 18 selected plugins. When the plugin installation finishes, NetBeans will automatically restart. Don't worry about any exceptions you may see, because we haven't installed the SDK yet.
   
6. Quit NetBeans.

Step 4: Install the JavaFX SDK

1. NetBeans plugin files (nbms) are standard zip archive files. One of the plugins downloaded was the SDK for OS X. Assuming you're still in the javafxnbms directory:
   

bleonard@opensolaris:~/javafxnbms$ unzip org-netbeans-modules-javafx-sdk-mac.nbm
  ...
  inflating: main/main.properties    
  inflating: main/org/netbeans/javafx/install/Install.class    

2. Create a directory under NetBeans for the JDK.

pfexec mkdir /usr/netbeans/javafx2

3. Copy the contents of the extracted plugin to NetBeans:
   

   pfexec cp -r netbeans/* /usr/netbeans/javafx2/

4. Make the SDK's binaries executable:
   

   pfexec chmod +x /usr/netbeans/javafx2/javafx-sdk1.0/bin/*

Step 5: Learn/Play

Start NetBeans. There are a bunch of JavaFX Sample projects. To create one, select File > New Project and then Samples > JavaFX under the categories. For example, here's the DisplayShelf (click to zoom):

To get started with learning JavaFX, check out the tutorials.