Based on my calculations the current network rate of the namecoin network is only around 65 GHash/sec looking at the number of blocks found in the last 24 hours.
I look up the current dificulty and estimates at
http://dot-bit.org/tools/nextDifficulty.phpI didn't see anything on that page for total network hash rate. Also I think their numbers are skewed because of the rapid decline in miners after the difficulty switch.