If I'm not mistaken, the rules only say that the reward can't be above the per-block reward at the present position on the curve. In fact, I believe there's been at least one block with less than 50BTC reward in it, and it was accepted just fine.
Yes, but what if you
are mistaken?
I'd be interested to see a pointer to the code in the client that checks the coinbase reward, if anyone is able to post it. I'd also be interested to see the block number of the legendary block with less than 50BTC reward in it.
[edit: The wiki has a
Protocol Rules page which is consistent with what elggawf said:
"when the transaction is accepted into the memory pool, an additional check is made to ensure that the coinbase value does not exceed the transaction fees plus the expected BTC value (50BTC as of this writing)" ]