No more. Steve Elledge has published a new technique for cloning that allows simple movement of DNA into a new vector without the use of ligase. His method, published here in Nature Methods, allows easy manipulation of any piece of DNA into any vector. The required amounts of DNA are at least 10 fold lower than any equivalent method with ligase (he uses only 2-3 ng of DNA) but he can also assemble 10-pieces of DNA simultaneously, and get 25% of the resulting products being correct! This is a revolutionary step forward. You heard it here first: Topo cloning is dead. T4 DNA ligase sales will plummet. DNA 2.0's services will become much cheaper, or they will go out of business. And the lives of molecular biologists everywhere just became much, much easier.
I cannot emphasize enough how important this is. This is a second revolution in cloning technology.