http://www.brewingscience.com/
http://www.brewstersyeast.com/Products.asp?id=2
I've only used Brewsters, but they're down the road from one another, wonder if they aren't connected somehow.
I've never used their "liquid" yeast, but I've prop'ed from a few slants and it's real yeast. Nice for something different that not everyone else is using. Getting ready to split a strong ale (see my HopGobblin' recipe) and split it three ways with CL-150, CL-210 and some yeast I got from a bottle of Ridgeway bitter, turns out to be the brewmaster from the defunct Brakspear Brewing. Should be interesting. I also found an agar plate that had been left exposed in my garage, growing these beautiful fluffy cultures of what sure look like cerivisae to me, so I'll throw them in some wort and if it makes "beer" I'll give some of the strong ale to that yeast to feed on. Sorry for the tangent!!! ;D