Does iTunes in the Cloud/iTunes Match have any effect on syncing ratings between devices?
I'll check my computer when I get home, but everytime I update the ratings on my iPhone there is definitely network activity (The network spinner is displayed everytime I change the rating). So it is definitely updating the iTunes Match library. Whether it updates the PC at home I'll have to see.

I'm still waiting for it to upload about 600 songs.

Edit:  I confirmed that ratings and play count  definitely are updated right away. PC to device changes take a little longer. I had one song disappear from my phone on my way to work because I accidentally removed it from match the night before and it took some time to propagate.