Their domain records say:
tradehill
2415 mission st
san francisco, CA 94110
US
2415 Mission St, San Francisco, California.
The mail drop place is 2417 Mission. 2415 is probably above "Wholesale Fashion Shoes".
This is Jared's "hacker hotel":
20mission "Hacker Hotel" above the T-Mobile store.
Same building, different entrance. Mission St. on the right, 20th St. on the left.
20mission lists Tradehill as a tenant. That may be where they really are.
Could be worse. PayPal started above Palo Alto Bicycles on University Avenue in Palo Alto.
20 Mission is a hackerspace/apartments. The most popular SF Bitcoin meetup is usually held there. http://www.meetup.com/San-Francisco-Bitcoin-Social/#past
They are indeed at 1 Market Street. My schedule didn't line up this week or next week so it may be about 9-10 days until I can make it there.
They focus on high net worth individuals. Typically these type of investors want to work with a company that is reputable. 1 market street has that.