https://blockchain.info/charts/n-transactions?showDataPoints=false&timespan=all&show_header=true&daysAverageString=1&scale=0&address=

This is interesting in the context of the ongoing maximum blocksize debate. Currently the maximum size per block is 1MB. Originally, there was no maxsize, but Satoshi added the 1MB limit to prevent spamming the network. He stated that the limit could be increased at a later date.

It can be phased in, like:

if (blocknumber > 115000)

maxblocksize = largerlimit

It can start being in versions way ahead, so by the time it reaches that block number and goes into effect, the older versions that don't have it are already obsolete.

When we're near the cutoff block number, I can put an alert to old versions to make sure they know they have to upgrade.

https://bitcointalk.org/index.php?topic=1347.msg15366#msg15366

This increase in transactions is moving the average block size closer to 1MB.

https://blockchain.info/charts/avg-block-size