2.5.4 patch6 2.5.3 patch9差し戻し

だそうです。近いうちに修正版と差し替え予定。(4/18日時点での情報。後日差し替えられてると思われるのでこの記事に意味は無くなります)
2.5.x導入済みの環境に既に当ててしまった担当者の方はご注意を。
http://www.vmware.com/support/esx25/doc/esx-254-200703-patch.html
http://www.vmware.com/support/esx25/doc/esx-253-200703-patch.html

In an environment where Windows and Linux virtual machines are configured with vmxnet virtual NIC driver, when the virtual machine is either powered off, suspended or migrated live via VMotion to another host, a small amount of memory is not freed. Hence, multiple virtual machine power-offs, suspensions and VMotions may cause the host to run low on memory.

A replacement patch which fixes this issue will be released soon.