"Dalvik has been written so that a device can run multiple VMs efficiently. The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimized for minimal memory footprint. The VM is register-based, and runs classes compiled by a Java language compiler that have been transformed into the .dex format by the included "dx" tool," reads an official about Android for developers. "The Dalvik VM relies on the Linux kernel for underlying functionality such as threading and low-level memory management."

There had been speculation in the past over a possible legal challenge from Sun over Dalvik, and given Android's success, it's no entirely surprising to see Oracle get litigious, IDC analyst Al Hilwa said. However, the fight could seriously harm Android at this point in its development, he added.

"Many expected Sun to raise some hay about Google's fork of the Java code to produce Dalvik, but having waited for Android to be a success can be quite disruptive," Hilwa said via e-mail.

"This is a typical intellectual property value defense lawsuit, but it can have serious consequences on the Android market and its adoption by OEMs. Basically, it says that Oracle wants to get into the action and leverage its acquired Java assets better financially," Hilwa added.

Oracle's lawsuit didn't surprise James Gosling, widely considered the father of Java. "During the integration meetings between Sun and Oracle where we were being grilled about the patent situation between Sun and Google, we could see the Oracle lawyer's eyes sparkle. Filing patent suits was never in Sun's genetic code," he in his personal blog, which at press time seemed to be offline.