Is it not clear that Samsung/ATT have decided that Galaxy-S GPS "is what it is," and they intend to leave it as is--or are unable to improve it?
I suspect that they, especially Samsung, do not want to divert manhours from new product development to work on fixing an already-deployed phone that (in their minds) works 95% OK.
ATT is now focused on trying to get Windows Phone 7 products out the door, and, further, Captivate is likely in steady-state sales. The initial glob of buyers have already done so. Thus, the future sales until discontinuance is probably pretty small compared to total ATT phone sales. So, sadly, from a business standpoint, why dump major effort into a dying product?
Conclusion: we are stuck with a potentially great Android phone made definitely-not-great by a randomly defective major function in it. And it won't get better. If it was just a matter of software fix, it would have been done and over. There's been enough time. So sad. They blew it. Big Time.