I can't specifically speak to Yosemite, but I just got back from a trip to the High Sierras and met several folks who were backpacking through there. They said that there was still a ton of snow and river crossings were treacherous at times. Knowing this, and the fact that the rainy season was a long one, seems to suggest that the water falls are still good right now.
The waterfalls this time of year are typically pretty dry, but we had a long rainy season this year. There's a good chance to still see some water, but if want to get drenched going up the Mist Trail, it's probably unlikely.