Sony has released a firmware update for the Sony A230, A330 and A380 DSLRs.  The firmware version 1.10 addresses the following:

When the [Metering mode] is set to the [Center weighted] or [Spot] metering modes, the exposure will be locked when the focus is confirmed. (When shooting in AF mode).

To learn more about the update or to download it, visit Sony’s download site for Windows PC or for Mac.