Starting with 11gR1, OWB users work in a workspace as opposed to having their own repository schemas as found in Oracle10g.  All of the workspaces are owned by the OWBSYS account and are managed or stored within OWBSYS's schema.  This greatly simplifies management of OWB objects within the database.  Users within the database can be added as OWB users via the granted role of OWB_USER.  It's more than just granting a role, management of OWB users should be done within OWB. 

As far as installing OWB is concerned, two operations are worthy of note.  The first, and probably foremost, is that OWB is installed along with the RDBMS software.  No more companion CD and starting up a separate Oracle Universal Installer session.  The installation of OWB is clean, simple, and transparent. 

Given that virtually all database users use a PC for things related to using Oracle, OWB has a client installation that is also quite streamlined.  If installing OWB in a simple architecture, where both client and server are on the same machine, the client software is also installed along with the RDBMS software.  In a split architecture, where the client really is a client and not on the server, then the standalone client installation comes into play. 

The other installation step or operation of note concerns the installation of Oracle Workflow Builder (the "other" OWB).  Oracle Workflow is an optional configuration of OWB.  If you want to use scheduling, you will need OWF.  In the days of 10g, this meant yet another OUI session with yet another CD/DVD.  The installation of OWF 2.  6.  4 isn't exactly one of the easiest Oracle products to install (but there are and have been worse products, trust me on that).  Using 11g, that story changes dramatically.  Installing OWF is amazingly simple.  You run a script and up pops a Java window asking for some connection information (use the host:port:sid syntax instead of pasting in the TNS entry).  About 10 minutes later, voila, OWF is installed. 

Going back to the client software for a moment, the configuration steps for using a 10g database with the 11g OWB software is a simple matter of running one or two scripts found in the client software tree.  Oracle has also conveniently provided a cleanup script in the event you need to flush the 10g database of OWB. 

Speaking of Oracle 10g (and 11g while we're at it), the certified versions are Standard and Enterprise.  Nowhere in the documentation will you find support for Oracle Express Edition.  Oracle XE is great for pure database stuff, but its ability to support sophisticated products is somewhat limited.  The first failure observed while running the cat_owb.  sql (used to configure 10g for 11g OWB) is related to DBMS_JAVA not being found.  Oracle XE doesn't do Java, at least not at the level OWB needs. 

There are plenty of hacks for getting Oracle products to run on not quite supported platforms, and it may be possible to install Java in XE by running the initjvm.  sql script found within an RDBMS installation.  Adding or installing an advanced feature into Oracle XE has many issues, two of which revolve around support and licensing.  As a comparison, you can get Oracle Business Intelligence Enterprise Edition (OBIEE) to run on Windows 7 by changing the compatibility mode property within the setup.  exe file.  That's close.  Hacking major functionality into a watered down product to begin with is something else. 

The learning options for Warehouse Builder are still fairly limited.  They include Oracle University, a CD from Oracle University (it's several hundred dollars), or Oracle by Example (the OBE section at OTN), and there are a few books out there on the subject.  A better option might be to look at third party training from Burleson Consulting.  Check it out at  http://www.dba-oracle.com/cou_oracle_warehouse_builder_training.htm .

So far, so good for OWB, right? Well, that depends.  There are OWB-related links at OTN, which take you to products related to OWB, but not directly to OWB.  For example, select Warehouse Builder in the Products A-Z list and you land on a page with "Oracle Data Integrator Enterprise Edition" being the most prominent text on the page.  The deal on this is explained in a roadmap whitepaper (ORACLE ? WAREHOUSE BUILDER PRODUCT ROADMAP). 

Oracle Data Integrator (ODI), formerly known as Sunopsis, was purchased by Oracle several years ago.  The growth and advent of ODI in Oracle's product space means OWB may lose some of its identity when the two products are more integrated down the road.  Customers have invested lots of time, money and effort into integrating these tools within the workplace.  According to Oracle, "... a future release ? will deliver a unified data integration product that protects customer investments in both products." OWB will be around for a while, but you may not recognize it, once ODI is combined with it. 

Additional Resources

Oracle Warehouse Builder 11gR2 New
Oracle Warehouse Builder (OWB) Weblog