Can miners who mine in a pool ignore the request to revert their bitcoind to 0.7, and stay with 0.8? As far as I know, it's the pool that counts in this case.
(Except P2Pool, which behaves a bit differently)
Miners who use a pool don't necessarily even have bitcoind. They use separate mining software (which does not constitute a node, or build blocks or anything of the sort) and the bitcoins they receive are first credited to the pool eWallet, and can then be withdrawn to any wallet.
The pool is the one choosing the blocks and even if the miner's wallet happens to be bitcoind it has no influence on this process. So there is no reason to downgrade.