This is an old post, but I thought I'd chime in here for those reading this thread for info on a WLP001 peach flavor.
I'm currently fermenting an amber ale that started at 1.056 and am using WLP001. The blowoff was pretty impressive. I took the blowoff container off and dumped the contents to clean it and found a huge amount of yeast on the bottom. I called my 6 year-old son over, who's always interested in my beer brewing (good chap!). I said, "Smell it!" He did and said, "It smells like peaches!" I furrowed my brow and took a sniff. Sure enough... fruit! Well, a hoppy fruit smell.
So I went here to read up on WLP001 and see if others have noticed this. So far, after reading about 60 threads, I've found some people have. The OP of this thread indicated he used Centennial hops, which is what I used. My ferment temps have varied. I pitched at 65 F, it took off within five hours (used a decanted 1.6L starter on a stir plate), and temp dropped to 63 F. Last night it went down to 60 F. I've raised it to 67 F and will hold it around this range before raising it to ~72 F towards the end.
Other posts that indicate a peach smell say it happens at lower ferment temps, but I'm not sure if that's true. A slew of posts indicate they've fermented at ~60 F temps, and none indicated a peach smell. I'm beginning to think it's the hops.
I did first wort hopping of .5 g of Centennial at first runnings, then boiled for an hour. After flameout, I cooled it to 110 F and added the other .5 g and steeped that for 10 minutes or so, then transferred this to the fermenter. I'll finish with a 1g dry hop addition of Cashmere for three days, remove it, and perhaps another 1g for three days, and then I'll keg it.
My hope was to get fruity characteristics from the hops to accent the malt profile in the grain bill, yet ferment using a more neutral yeast. WLP001 seemed like a decent yeast to use for an amber ale.
Peaches? I'm starting to think perhaps its from the Centennial hops and the way I used them pre- and post-boil.
Any other comments from the folks, please chime in! Comparing experience is the best way to learn, along with actually brewing.