Earlier today the Difficulty threshold for generating Bitcoin went from 14484 to 16307. The difficulty readjusts every 2,016 blocks and today this happened today at block 10,800.
This puts the hashing strength of the entire Bitcoin network at roughly 120 Ghash/s. While it is difficult to compare this performance to the levels that supercomputers provide, or to that found in other distributed computing projects, Bitcoin''s hashing growth rate is likely unparalleled for projects of this size.
At the end of the day, this means that my share of the network has dropped and it is taking longer and longer to generate a block. To see more regular payouts, one option is to join the mining pool. Or to start looking at more hardware.