To say that the concepts of true and false do not apply to moral statements is not the same thing as saying that ethics is meaningless. For one thing, one can be committed personally to a particular ethical view without necessarily believing that there is any objective criterion by which it is superior to others. Also, ethics serve a real world purpose in co-ordinating the behaviour of agents with different goals; one can judge the efficacy of moral systems in fulfilling this purpose without necessarily either approving of it or making the mistake of confusing utility with truth.
Putting these together (actually the first is sufficient, but I threw the second one in anyway), one can both be in favor of some set of real world consequences, and judge moral systems on how well they promote these consequences (ie be a consequentalist) without making the mistake of attributing objective truth (or whatever) to the moral systems you therefore favor. There is thus no contradiction in being a consequentialist and denying the existence of any objective morality.
My intended next OB post will, in passing, distinguish between moral judgments and factual beliefs. Several times before, this has sparked a debate about the nature of morality. (E.g., Believing in Todd.) Such debates often repeat themselves, reinvent the wheel each time, start all over from previous arguments. To avoid this, I suggest consolidating the debate. Whenever someone feels tempted to start a debate about the nature of morality in the comments thread of another post, the comment should be made to this post, instead, with an appropriate link to the article commented upon. Otherwise it does tend to take over discussions like kudzu. (This isn't the first blog/list where I've seen it happen.)
I'll start the ball rolling with ten points to ponder about the nature of morality...