Don't know of any forum discussions on this, but you might search on "PlaceBase" and/or "C3 Technologies", both of which were acquired by Apple. Whether or not these are what replaced Skyhook I can't say for sure, but I do know that Skyhook is no longer used as of iOS 5. My guess is that the wi-fi location service problems are due to errors in whatever database is being used.
Also note that even if you're on 3G your iPhone may still be using wi-fi to triangulate your location, even though you're not actually connected to networks that your iPhone can see. This may explain location errors even while on 3G. If you turn off wi-fi entirely, and maybe re-boot your iPhone to clear out any residual data, you might find that the location error goes away.