Hot off the presses! Even as rumors swirl about the fate and future independence of a number of open-source software start-ups, an acknowledged leader in the latest wave of open-source development, MySQL AB, has raised $18.5 million in its latest round of funding.

Both this financing and the speculation over a $700 million roll-up by Oracle of as many as three different open-source start-ups reflect the choices early-stage companies face between independence and acquisition.

At MySQL, the decision to raise capital was all about sending a message of independence to its customers and the market, according to the company’s chief executive, Marten Mickos. “A strong balance sheet is a great thing to show to customers or partners,” he said. “Just to show ‘hey, nothing can rock this boat.’”

To that end the company, with its U.S. headquarters in Cupertino, Calif., raised its Series C financing from the California venture firm Institutional Venture Partners, along with a slew of corporate partners including Intel Capital, Red Hat Inc. and SAP Ventures.

MySQL has developed an open-source database software product that it licenses to other technology developers and sells as a subscription service. Traditionally the company made the bulk of its revenue from the licensing business, where its database software has been embedded in technology like the intrusion detection product from Cisco Systems Inc. Now, it’s seeing fastest sales growth from its subscription business, which includes customers like Bank of America Corp., Caterpillar Inc., and Cox Communications Inc.

While MySQL has decided to build its business as an independent concern, companies including Atlanta’s JBoss Inc., Israel’s Zend Technologies Ltd., and the Emeryville, Calif.-based Sleepycat Software Inc. are all reportedly flirting with acquisition offers from Oracle Corp.

Cheers.