Here is a sweet little block explorer tweeted by Zooko (although it gets the hash rate value completely wrong and unit wrong too--It's Sol/s not H/s and it's about 400 Sol/s right now):
https://explorer.zcha.in/ Edit: it gets this info from zcash itself (zcash-cli getmininginfo) which is probably buggy and doesn't compute the network's speed correctly.
My Equihash PoW solver silentarmy gets 45 Sol/s on an R9 Nano, so there seems to be only about 10 GPUs mining worldwide, 65 minutes after the launch of Zcash :)
Edit: oops scratch everything I said. I forgot difficulty 1 was redefined for the mainnet. In testnet difficulty 1 was defined as:
genesis.nBits = 0x200f0f0f;
So you needed the 32-byte SHA256 hash to be less than 0x0f0f0f00_00000000_00000000_... But with the mainnet it was redefined as:
genesis.nBits = 0x1f07ffff;
This value is 0x0007ffff_00000000_00000000_... so only 1 in 8192 random hashes is less than this. So the network's speed seems to be around 130,000 Sol/s. So that's already 3-4k GPUs mining. Ouch.
My Equihash PoW solver silentarmy gets 45 Sol/s on an R9 Nano, so there seems to be only about 10 GPUs mining worldwide, 65 minutes after the launch of Zcash :)
Edit: oops scratch everything I said. I forgot difficulty 1 was redefined for the mainnet. In testnet difficulty 1 was defined as:
So you needed the 32-byte SHA256 hash to be less than 0x0f0f0f00_00000000_00000000_... But with the mainnet it was redefined as: This value is 0x0007ffff_00000000_00000000_... so only 1 in 8192 random hashes is less than this. So the network's speed seems to be around 130,000 Sol/s. So that's already 3-4k GPUs mining. Ouch.