Oracle CEO Larry Ellison appears to be taking a lesson out of the playbook of his buddy, Apple CEO Steve Jobs.

Ellison tantalized Wall Street this US summer with promises of a "major database innovation" to be announced this month, presumably during the company's annual OpenWorld conference in San Francisco, which starts Sunday.

"It is going to be a very big and important announcement for us, so we are not standing still in database," Ellison said.

Oracle is releasing its first-quarter earnings Thursday, and executives could reveal more tidbits during the accompanying conference call.

At the same time, Oracle has been more secretive than normal, presumably to build interest in this upgrade, the R2 (release 2) of its year-old 11g database.

The number of companies invited to the beta program is smaller than in years past, sources said. Those who did participate uniformly declined to reveal details about R2's features via their blogs or to reporters.

Moreover, in at least four cases, information about 11g R2 that was posted to the Web by Oracle or outside bloggers has been taken down, though evidence in Google's search cache often remains.

"I've never seen anything like this," said Paul Vallee, CEO of The Pythian Group, a Canada-based database services provider. His company was not invited to participate in the 11g R2 beta, despite having participated in every other recent one, he said.

An announcement about 11g R2 is expected at OpenWorld, though several bloggers and commentators (see here and here) say the upgrade to the market-leading database is unlikely to be available until 2009.

So, what new features will arrive in 11g R2?