Craig Lemle, corporate managing director of Julien J. Studley Inc., which represents the owner of the former Boo.com HQ, says in this market, "I think most owners would like to get space back. If a tenant says 'I'm thinking of closing my doors,' the owner says, 'You won't have any trouble from me.' It's already built and they can lease it out for a higher rent."

Boo.com was paying in the mid-$20s per sf. Its successor, probably another Internet company, will pay double, Lemle says. He expects the space to be occupied in about a month. "It has open space, a view of the river and the computers are still there," he adds.

In such cases, tenants benefit because, although their rent will be substantial, they don't have to spend money on improvements. This is particularly true of high-tech firms, which need expensive communications wiring. Owners profit as well since they have the prior tenant's security deposit.