The latest release Beta 1.5 of Minecraft introduces several new things that need textures: powered rail, detector rail, and two new sorts of sapling. I added them first to Texturejam’s patches pack—used to upgrade other packs to Beta 1.5—and did not get around to doing GroovyStipple versions until today.
The new Beta needs a new side-grass texture. Like the grass texture, this is greyscale and is colorized with the biome grass colour, and then superimposed on the old side-grass tile. I have changed the side-grass to have a zig-zag edge and an improved stipple.
For the powered rail I made another attempt to design something that looks like it has a rotating element in it. I am not sure it quite works, but it will do for now.
To install them, click on Mods and Textures in the Minecraft main menu, use it to visit the textures directory and copy or move the ZIP files there.