Prepare to be underwhelmed, as the latest firmware addition to the PlayStation Portable jumps from 3.72 to 3.73. What thrilling additions have inspired the hundredths jump to 3.73? According to Sony, the "operation of the UMD drive has been improved to address cases in which the UMD drive occasionally suspends and fails to load data." If that sounds like you, hit up the System Update page and enjoy your download.
The above picture is, of course, unrelated and does not make Gran Turismo 4 Portable anything more than vaporware.