I've only been able to find one commercial Berliner Weiss-style beer in my area and that is 1809, brewed by Dr. Fritz Briem of the Doemens Institute (a brewing school in Germany). I bought the beer figuring I'd taste it and then maybe pitch the "dregs" into the secondary fermenter of my Berliner-style Weisse.
Upon pouring this beer into a goblet (old Falstaff glass), I immediately caught a whiff of the same smell I remember from the sour mash of my homebrew. An almost sour milk-like aroma, yet sweeter and mixed with some light floral hops, and therefore not as offensive. The lactic sourness and fruity complexity of this beer actually reminds me of a beer from New Holland Brewing Co. a couple years ago called Pilgrim's Dole. If I could pinpoint the flavors, it would be a sort of pineapple fruitiness combined with the lactic sourness. This would indeed be a very quenching brew a warm day. The body is very light, the finish dry and tart, with very little hop character. A very refreshing brew that is definitely worth a try.