Many economists do support the land tax, but think it is too low to support government functions.
Why can't the rate just be set higher?
When the tax approaches the rent of the property, the capitalised land value drops to zero. If the land tax is based on percentages, you'll have the rate escalating way beyond 100%. No problem for homo economicus, but most real world people would be shocked by seeing property tax rates of 100000%.
Tangential, but a subject of some local interest:
Why Bitcoin will fail by Avery Pennarun. "The sky isn't red." Thesis:
I'm not sure I buy these and am not competent to evaluate his claims on 3., but would like others' critique.
L019: Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen by Jason Calacanis. A rather more enthusiastic viewpoint of the project:
The actual text contains many more caveats than the eye-catching selection of points above.