What is the difference (or relation) between a Bitcoin "Block" and a GPU workunit called a "Block" I'm looking at OpenCL and GPU programming and see the term "Block" used to describe a unit of work sent to a GPU.

What is the relation between a Bitcoin Block and a GPU workunit called a block?  

If there is a relation, was this intentional?
No, these two terms are completely unrelated.

Bitcoin block is a record of some or all of the most recent Bitcoin transactions that have not yet been recorded in any prior blocks.

GPU block is just an unit of organization of threads running in parallel. The threads running on GPU are organized in blocks, and threads belonging to same block have effective means of interacting with each other. The size of single block and number of blocks affect application performance, and optimal parameters differ between different hardware. Surprisingly, while most GPU miners are written in OpenCL and not in CUDA, the 'block' term comes from CUDA and OpenCL specs use 'workitem' to refer to this concept.