I see that Adobe AIR uses WebKit as its render and I see that WebKit (at least the most current build) has some SVG support. Does this mean (and has anyone specifically tried) that an Adobe AIR application could render SVG on an HTML page?
No, not at this time.
See: http://help.adobe.com/en_US/AIR/1.1/devappshtml/WS5b3ccc516d4fbf351e63e3d118666ade46-7ec1.html
On the offchance that it's helpful (and that you don't already know), Flex can embed SVG at runtime compile time, which effectively converts it to SWF format and embeds it as a resource.
[Embed(source="assets/frog.svg")]
[Bindable]
public var SvgAsset:Class;
More info at Adobe's embedding assets article.
If ActionScript 2: use the com.itechnica.svg (PathToArray) library to load SVGs at SWF runtime and display them (uses XML for SVG parsing):
Using SVG Path Data in Flash, Download button on the right pane.
If ActionScript 3: use the com.zavoo.svg (SvgPath) library to load SVGs at SWF runtime and display them (uses RegExp for SVG parsing):
Source code for SvgLoad and SvgDraw, Download button on the bottom-left.