In less than a months time the fix put into place to prevent a fork like the one on the 11th of March will no longer be in place and miners will again be able to make large blocks that will be rejected by version 0.7.2 bitcoind software or earlier.
The fix, put into place on the 18th of March when Gavin Andresen released Bitcoin-QT and bitcoind version 0.8.1 made it so that all blocks made were compatible with older versions of the software will expire on the 15th of May so it is imperative that if you run bitcoind downloaded from the official website you upgrade to 0.8.1 as soon as possible (before May the 15th at the very latest).
Do I need to upgrade?
only affects people running the full bitcoin reference client downloaded
from the official bitcoin.org website as pictured
to the right. You can check what version you are running
by selecting 'Help' and then 'About Bitcoin' from the menu, if the first
lite reads anything else but "Bitcoin version v0.8.1-beta"
you need to upgrade.
How do I upgrade?
Once you have downloaded it, run the setup file and follow the installation prompts.
It is quite likely that if you do not upgrade that in the near future a block will be generated that you bitcoin client cannot process. If that is the case you will no longer be able to download future blocks and your client will stop being able to process the block chain.
You will effectively be stuck at that point and in order to progress you need to upgrade your client.
What's the worse that can happen?
If there are miners using the older version of bitcoind there is a possibility of another fork. Fortunately it seems that all major pools have upgraded though and if there is a fork it will be ignored and those blocks (and rewards) on the fork will become worthless.
It is unlikely that bitcoin will revert the older block size like it did last time so everyone needs to upgrade their clients.
Is there another way to make my pre 0.8.1 bitcoin client compatible?
Yes, if for some reason you cannot upgrade to 0.8.1 you can follow these instructions from the bitcoin.org website;-
If you cannot upgrade to the latest version, you can still avoid the problem. Create a file called DB_CONFIG in the bitcoin data directory, containing these two lines: