If you are trying to update to WordPress 3.0 and you are frozen on "Downloading..." or seeing "Fatal error: Allowed memory size exhausted" errors, don
The size of the download package for WordPress 3.0 is a bit larger than previous versions, due to the merge with WordPress MU and the awesome Twenty Ten theme. WordPress needs a bit more memory to download the larger file, which this plugin handles.
Your host may prevent PHP from increasing its own memory limit. Please contact your host. WordPress recommends at least 32 MB, but it may need a bit more during an automatic upgrade. This plugin bumps the theoretical limit to 256 MB, though we'd never need that much.