A great source of vegan probiotics can be found in fermented vegetables. At my natural food store there are a number available: cabbage, daicon, beets, carrots. They are not pickled, but naturally fermented; to retain their benefits, they should not be cooked, as that kills the bacteria (you probably realize that, but just thought I'd mention to be sure). I use these on my salads and in my smoothies. I love the daicon! Carrots are my least favorite. :-P
I have read that you can make these yourself and that it's not difficult, but I haven't tried yet.
Hope this helps!