According to the post at http://bitcoin.stackexchange.com/questions/2035/limit-size-of-data-files, a blk####.dat file should not go above 1GB. Mine is 1.5 GB. I haven't been able to find any info about this apparent discrepancy.
My over-active mind is assuming that those who lose out because of the freedom Bitcoin provides are hard at work on schemes to make it infeasible. One such scheme is to flood the block chain with transactions. That's why I started looking at the size of the data file.
Ths size grows over time and even if 1.5GB is perhaps a little too large (even depends a little on the used filesystem), I can confirm mine is currently 1,43GB in size! You can safely close this.
It seems more likely that the client (bitcoin qt 0.6.2) doesn't create the second file when it should (around 1GB), but I suppose the 1GB might just be a bad guess about the outcome of some calculation on Pieter's part, if it's written to start a new file based on some trigger other than the current file size.
The threshold for another file is closer to 2GB. As for the size, most of the recent rapid growth is this really transaction inefficient gambling site called satoshidice, the second biggest is deepbit mining pool's inefficient daily payouts (with about 25% of the transactions before satoshidice began).
Ultimately it seems that greed and ignorance are always bigger enemies than evil.
Database file size will always be large, whether it is 1GB or 2GB etc.
Each blk????.dat file will grow to 2GB, and then a new blk????.dat is created and appended-to.
The growth of blk????.dat is directly a function of keeping a copy of all bitcoin transactions on local disk.