What I've got now is a frozen pond in my village, with the reflections fuzzy and vauge on the snow, but sharp on the pool surface and pathway.
The reflected objects are drawn into a reflection texture, then the ground sprites are drawn, then the reflection is blended over the top with the reflection shader. The reflection shader does a variable blur (just the usual growable disc filter) based on a 'sharpness' texture, which is manually created to specify where the reflections should be sharp and where not. The sharpness also affects the transparency of the reflection, so sharp reflections are more visible than fuzzy ones.
You can see how the larger snowball has a sharp reflection on the pool but fuzzy otherwise. I've not finished tweeking it yet, I might make the snow reflections a little bolder. And after that I've got to write a GL 1.1 fallback path and use that when GLSL isn't available.