The only way that I've been able to sex mine is that the female is much larger than the male. If you have one (or more) of each sex that are old enough to spawn, it'll be obvious. My male is younger than the female, so I thought that was why he was smaller, but that wasn't the case. I only have 2 of the albino cories right now, but I'd like to get more soon.
I also have 3 panda cories and I think I have 1 female and 2 males. One of them is definately larger than the other. They haven't spawned yet, but I can't wait until they do. I think with any cory, the females are larger than the males.