2.5% donators (calculated on a per block basis) are able to claim their rewards without waiting for 120 confirmations of the block. This also acts as invalid protection, similar to DeepBit, where a user can claim rewards even if the block is later invalidated/orphaned by the network.
BTC Guild first opened up on May 9th, 2011. It is currently for sale and a possible buyer has been found. There is a 90 day notice period. If the sale does not go through, another 90 day notice period will be announced. 30 days for the pool to stop operation and an additional 60 days for users to withdraw their mining proceeds.
On June 15th, 2015, it was announced that BTC Guild will be shutting down on June 30th, 2015. Its operator - Eleuthria - cited concerns over low percentage of network hashrate vs funds in a hot wallet, the New York Bitlicense and possible but difficult to prove gaming of the pool by miners.
- BTCGuild web site