You know, I'm not sure WHY SecondLife hasn't included a grass transform... it would make many places in SL much more beautifull if we could specify an area to have grass.
What I would LOVE to see is grass height based on the same sort of system that land height in Sims is based on. You upload a picture and the whiter the spot the higher the grass, up to some maximum amount. That would allow people to quickly put down grassy area's while still leaving Roads and Water ungrassed, and do it with a single texture. You just use black where the places you DON'T want the grass to grow.
An alternative could also be to make different types of grass different colors in the map so that dark blue is no/short grass of one type, light blue is long grass of the same time, dark green is no/short grass of another type, light green is tall grass of the same variety as the dark green...
As a person who loves nature and wants to include nature in my sim I would LOVE to see grass as a transform (supported by most high end graphics cards) rather than as an object.