You don't even need to be that rich to have an assistant 24/7:
Personal Assistant™
Offers MasterCard® Black cardholders the convenience of a personal assistant, 24 hours a day, 7 days a week. Going beyond the service of a concierge, Personal Assistant is available to free up time for busy cardholders, with services such as:
Child care services (such as pick-up and drop-off at school).
Pet care.
Personal shopper (domestic and international).
Location and purchase of rare gifts.
The MasterCard® Black Personal Assistant service will answer virtually any request that money and ethics can buy.
Crap, this could have really saved me over the last month - what's the catch? Have you used something like this? I think my last card had it (calling it "Concierge") but my current bank doesn't mention it anywhere.
Typically cards with extra features either (at the low end) charge a monthly fee or (at the higher end) have minimum requirements such as a minimum net worth for the holder or a minimum monthly or annual spend through it. Lower end would normally be a small fee and fairly basic bonus features (travel insurance, gadget insurance, airport lounges) while I'd expect any half-decent concierge service to be aimed at attracting richer customers. The minimum worth/spend requirements basically mean the extra services offered are there to attract people who will give the card creators more % by spending more money, giving them enough profit to offer free services.
For free.