It's not listed on the Leica S2 site yet, but there is a new (16 001) focussing screen for the S2 due any day now. I was at the factory last week and they very kindly gave me new screen to try out, one with micro prisms around a split image centre. It's just like the screens used to be like in Canons and Nikons, and, with the fast f2.5 lenses, the ring of microprisms works very well.
I am quite used to the plain ground glass with the cross in the middle but having fitted this new one I will not be going back. I never had much trouble with focussing anyway (bright, big viewfinder) but now it's even easier. The 35mm was the least easy to focus critically by eye, but the microprisms really show up when the subject is bang on focussed.
Swapping it out is simplicity itself - the new screen comes in a small case with a clip tool to grab an edge lug. You just drop down the old screen, pull it out with the tool, grab the new one and slip it into place. It took me about 60 seconds.
If you Google "Leica 16001" you will see that B+H has it listed already, as do a couple of the more specialist online stores, for about $450. I'm not sure if it's fully available yet but they told me it would be released and shipped 'in a couple of weeks or so'.
