The manufacturer of the Turbo Twisting Block is very much in business - and doing quite well.
There are (as of last Saturday) 3 Blocks still available at Ted's Sport Center. Another dozen will be on their shelves in January of 2004. If enough interest in the tool is generated, they'll be available in better fly fishing shops in Puget Sound by Q1 of 2004.
Both HareLine and Orvis have stopped carrying the Block and none exist in their inventories to the best of my knowledge.
If anyone needs more details on the up-coming availability or a ringing endorsement on the Block, just drop me some private e-mail.