Recent history suggests for Sun's patents, not their software.

Oracle has claimed they bought Sun for their hardware (e.g. so they could do vertical integration selling like IBM), but that remains to be seen if it is true or not.

Oracle used Sun's hardware to build the Exadata - which they very aggressively sell as a data warehouse solution. Competing with Netezza, Teradata, Greenplum and the likes.

Well, Sun paid a billion dollars for the domain name mysql.com, when all's said and done.

Sun has a significant hardware business, especially in the legacy SPARC products.

Combining that with Oracle's applications turns Oracle into a complete solution provider like IBM & HP.

Solaris is open source, but Oracle has dropped support for the open source version and isn't going to open source all new features.

Sun also owned MySQL, which gives Oracle a great foot-in-the-door at a whole industry segment where they weren't a player before.

I wasn't claiming that Oracle maximized their shareholder value ;) In fact I'd argue that Oracle simply burned cash.

And perhaps it was just managers expanding their empire. You know, principal agent problems between managers and shareholders.

Sun has more patents than pretty much any company not called IBM. Oracle probably paid way too little for what they got.

Oracle uses a decent amount of Java. It was probably worth it just to control the language's standards and runtime.

But they still own the brands and for business people it matters. They can also develop various proprietary extensions.