Once upon a time, I wrote a blog entry about CircularString, CompoundCurve, and CurvePolygon (the new geometric types supported in Denali). And mentioned that they came from ISO-ANSI SQL/MM and weren't in the OGC spec. Well, lo and behold, while browsing the latest OGC Simple Features – Part 1 spec, the last incantation (version 1.2.1) does support 'em. We don't have all the OGC types (missing Curve, Surface, multi-versions of those, Polyhedral Surface, and TIN) but it's good to see the OGC support/add the ones we do have.
Speaking of the new types, I'm still looking for a visualizer for them. Spatial result tab was removed from SSMS CTP1 Denali, so I've got SSMS 2008 R2 installed. But of course that doesn't support the new geometric types, so curves, fullglobe, and types greater than a hemisphere large (these were added in Denali too) draw a blank. So I can draw them on graph paper. And in my mind… Neither Bing nor Google, that I'm aware of, support them. Wonder if SAFE FME visualizer does, hmm… You usually approximate them with linestrings/polygons, STCurveToLine and CurveToLineWithTolerance are your friends.