I can help a little bit. On the following pie chart, "Unknown" are small pools, dark pools, solominers and bot-nets. They've dropped from around 20% of the network hashrate a few weeks ago to about 10% now. So, assuming there are no botnets mining at pools, they are currently less than 10% of the network. As Difficulty increases, this percentage will decrease further.
I'd also assume that the only CPU mining on the network would be due to botnets, but I don't know how large a proportion of botnets would be CPU and how much GPU.
The first ASICs were added at the start of february. The Hashrate has increased by ~ 10 or maybe even 12 Thps since then. Some of those will be GPU miners that found they could still profitably mine after the constant increase in the exchange rate, but lets say 10Thps are ASIC. So I'd estimate ~ 28% of the network hashes are contributed by ASICs.
I'd guess GPU and FPGAs are probably about even, but I could be wrong.
It's an interesting question - maybe you could start a poll?