Gridworks sounds very exciting. Check out the screencasts linked from Jon Udell’s blog.
While Gridworks doesn’t attempt to penetrate the semantics of the source data, this is enormous progress from the feeble tabular-data import tools available on Swivel, Many Eyes, Timetric and other sites. From the demo I can’t tell whether it will be possible to save the set of transformation rules applied to one dataset and use it again later. This would be extremely useful for massaging periodic datasets every time the source is updated.
According to the Freebase blog, Gridworks will be released as open source next month.