This weekend, as I was brewing a batch of beer so secretive no more can be said about it, I cracked a bottle of my apple lambic. It was a beer I brewed up over a year ago, and to which I added, months later, apples from my front yard. It was remarkably good--the apples were evident in the nose, though subtle, and they drew out the tart wild yeasts. One might mistake the note they contribute for a fermentation characteristic.
Another note: this beer was wildly effervescent. I used the Wyeast lambic blend (great yeast, I highly recommend it), and in past batches, the liveliness oscillates between almost nearly still and slightly fizzy. Rarely have I gotten a sustained head. (The age of the beer seems to have nothingn to do with it--one month it's fizzy, the next still.) This one piled up a two-inch head, and it lingered. It sported a roiling bead, also unprecedented. Wild yeasts are so ... wild.