I came across the group San Antonio Street Art although the page hasn't been updated in sometime (April 2006)
Bexar County Line is also a great resource for any kind of street-art in SanAntonio. The site is updated on a daily basis, so that's another plus.
And one more thing, check out the write up from last year's Best of issue of the Current where we honored Scotch! with Best Anonymous Public Art for Tricycle Girl(s).
Fear not, as the blogs get shorter I am preparing myself for a sleepless night preparing for tomorrow's ultra-colossal blog entry complete with pictures of local street art and more obscure findings. Until then, go enjoy your Thursday night!