CORE COMMAND is the latest offering from Dream Pod 9, who have decided to combine the overhaul of their Silhouette game mechanic with a D20 conversion, with the intent of facilitating the use of all their game lines with one (well, 2) simple rulesets.
However, rather than merely rewrite the rules and bolt on d20, they've designed a whole new game, CORE COMMAND, to lanch the revised system.
CORE COMMAND is described as 'epic space fantasy' with vast starships, powerful technology that leaves your jaw dropping and big nasty alien monsters to threaten you (as if your fellows' plots and intrigues were not enough!).