I'd say it has been killed off; I'd say when push comes to shove, it was easier for them to base a new office suite on OpenOffice + Eclipse SDK than going out and trying to bring SmartSuite to Linux and Mac OS X.D
I would say moribund rather than killed off. Serious development stopped several years ago, but it is still supported on Windows and OS/2 with infrequent update patches being delivered - I assume some corporate customers still have not moved from Smartsuite onto other office packages.
The Windows version is still on sale, btw.