Matt burch owns the Escape Velocity name. You are welcome to create your own space ship game, so long as the name Escape Velocity or any of the triology's scenarios, or material from those scenarios, are used. If you wish to use either, you'll need to talk to him and probably Ambrosia as well. And for Nova you'll probably have to talk to ATMOS too. Otherwise you may endure legal reprecussions or, if you're lucky, be told to cease and decist, much like Diablo Hellfire was shutdown by Blizzard.
Escape Velocity Nova's last update was less than a year ago (7/10/06 specifically). It is still supported by Ambrosia and there very well may be a 1.0.11 version on a to-do list, considering there is at least on major outstanding bug still to date.
Whether I am for or against this remains to be seen.