A lot of people seem to be freaking out about GPU miners driving down the price of primecoins by driving up the supply rate. This is nonsense, GPU mining will not significantly increase the supply rate of primecoins and in the long run will make very little difference in the total mining rate.
Primecoin is designed to produce 1440 blocks a day on average, regardless of the processing power thrown at it (not entirely true, I'll explain in a bit). On top of that the number of coins per block goes down as 999 / d^2, where d is the difficulty. So for d = 7 each block gives 20.39 coins, d = 8: 15.61, d = 9: 12.33, d = 10: 9.99. The difficulty will be going up to 9 within a day most likely. The minting rate is going down and will continue to do so even after GPU miners are released because the supply rate does not depend on processing power (mostly).
You can get more info here:
http://ppcoin.org/static/primecoin-paper.pdfhttp://cryptometer.org/primecoin_90_day_charts.htmlNow for the disclaimer. The algorithm dynamically adjust for the amount of processing power and if there is a spike if will need to play catchup. During the catchup phase more than 1440 blocks will be generate a day on average. you can see this in the cryptometer link. The number of blocks is creeping down to 1440 after the initial spike.
What will change when gpu miners are released? Assuming the gpu miners are much more efficient than cpu miners then people running gpu miners will generate more coins than people running cpu miners. On average the coins are found in direct proportion to the share of the total processing power you have. Lets say you have 1% of the total mining power then on average you would mine 1 out of every 100 blocks or 1440/100 = 14.4 blocks a day. So if you are running a gpu miner that has 10 times the primecoin mining power as a cpu then you will get 10 times more blocks on average.
TL;DR GPU mining will not increase the rate at which primecoins are mined. There will be no flood of coins.