As expected, former Sun Microsystems CEO Jonathan Schwartz confirmed that he is leaving the venerable server and software company now that it’s been acquired by Oracle.

Perhaps less expected, Schwartz made the announcement late Wednesday night in the form of a haiku, via Twitter:

“Today’s my last day at Sun. I’ll miss it. Seems only fitting to end on a #haiku,” read the brief message from Schwartz, who uses the Twitter moniker OpenJonathan. “Financial crisis/Stalled too many customers/CEO no more.”

Schwartz, 44, has not said what he plans to do, although there has been speculation he might join a software startup or venture capital firm. The longtime software executive succeeded Sun cofounder Scott McNealy as CEO in 2006.

While at Sun, Schwartz led the company’s embrace of open-source software, pursuing a strategy of releasing the source code to many of its programs, in the hope that customers would become familiar with them and then purchase maintenance contracts and Sun hardware. Schwartz also sought to cultivate an iconoclastic reputation, wearing his hair in a ponytail and writing extensively about his views and corporate strategy in a company blog.

But Schwartz was not able to turn around Sun’s struggling business, as many customers turned to lower-cost commodity hardware and other vendors found ways to operate more efficiently. Some of Sun’s biggest customers in the financial services sector also cut back purchases during the recession.

Schwartz isn’t leaving the company empty-handed. Regulatory filings reportedly show that he was to receive $12 million as part of a severance package from Sun.

Oracle CEO Larry Ellison told The New York Times last week that he did not expect Schwartz to remain with the company, although Ellison reportedly said he hoped to find a role for McNealy. Oracle has retained another high-ranking Sun executive, John Fowler, who ran the systems business for Sun and will continue as the head of the hardware business for Oracle.

Contact Brandon Bailey at 408-920-5022.