And here we go!
Just a small note regarding RC1. It seems like there is a bug for the one available to download at the time I'm writing this guide. I recommend to use either previous release such as 1.1.6 and 1.1.7 or to use pentaho source from SVN (what I did).

Now, let's start our step by step approach of Penatho on Glassfish:

1. Download from svn the latest Pentaho release or version 1.1.7 from Sourceforge.
2. Download dom4j and jaxen:
1. http://dom4j.org/download.html
   
2. download version 1.6.1, unzip and copy dom4j-1.6.1.jar to your glassfish/lib dir.
3. http://jaxen.org/releases.html
   
4. download version 1.1 beta9, unzip, ant and the copy jaxen-1.1-beta-9.jar to your glassfish/lib dir.
   
3. Check that you have MySQL connector/J or PostgreSQL JDBC jar file in your glassfish/lib dir
4. Now move back to your pentaho_j2ee_deployment dir and edit the following files:
1. default.properties: change the rdbms parameter to mysql5 (or postgres or mysql4), put the proper value for solutions.dir when the solutions are not stored as a sibling dir of your application server and check various values such as JRE, etc.
   
2. web.xml (located in the webapp folder): there are 2 withe value SampleData, remove one. Check the value of with name solution-path.
   
3. hibernate.cfg.xml (located in res/hibernate/mysql5): adapt user and password to the one you are willing to use.
   
5. Go to the top of your pentaho_j2ee_deployment dir and launch ant compile in order to have the first part of your pentaho compiled.
6. I assume step 5 is OK, and not launch ant orion-ear
7. Create the databases and user(s) on your dbms server (Mysql5 in my case), for this step I suggest you to move to Pentaho forum and look for the post of the Mysql scripts. Use these scripts to create the following database: quartz, shark, hibernate and sampledata.
   Since you are creating database add the following one: pentaho, datasource1, datasource2, datasource3, datasource4, datasource5 (these databases are empty)
8. Launch glassfish
9. Create database resources:
1. Connexion pools associated to the databases you have created in step 7
2. Check (ping) all the connection pools
3. Create associated JDBC Resources
   
10. Now try to deploy the freshly created orion-ear.jar file using glassfish admin interface or autdeploy directory.
11. Go for a test http://localhost:8080/pentaho

If every thing is OK you should see something like this:

Nota: in order to make sure the right hibernate.cfg.xml file is used in you orion-ear.jar file you can check the build folder. If the one you are expecting in not in the redo ant compile and check again before doing ant orion-ear. If there is still no change just go for a hard change and copy over them the proper hibernate.cfg.xml files and go for ant orion-ear