I'm just going to share my raw numbers here and let the folks who are good at number crunching decide what they mean. I prospected 300 ore (15 stacks) and here's what came out of that:
59x Sparkling Shard
22x Tiger Opal
17x Pandarian Garnet
9x Lapis Lazuli
3x Wild Jade
You can see here that I'm ending up with 20 rare gems, which would cover about 6 days' worth of recipe discoveries. 300 ore can easily be collected in an hour, probably less. Which means an hour or so of farming time could supply your research gems for almost a week. If we assume 5 minutes/day in Cataclysm for each daily token, it would take you about 90 minutes (over 18 days) to get the same number of new recipes. From a time standpoint, we're saving 12 days and 30 minutes of in-game time.
Plus with Zen prospecting we get sparkling shards, which save us from spending daily tokens on our personal gem needs. This number of shards would buy me almost 6 chimera's eye if I had to acquire my gems from the vendor. I'm really pleased to see this change, because I no longer have to sacrifice new recipes in order to gem my own gear.
I hope this information helps those of you who were wondering about prospecting. If you have any questions on prospecting ore, please leave them in the Comments!