Despite the vague changelog, the homebrew and developer communities (such as those on PSX-Place) identified the primary purpose of the update:
PS3 Firmware 4.88: A Complete Guide to Downloading and Installing ps3 firmware 4.88 download
For users utilizing Custom Firmware (CFW) or PS3HEN (Homebrew Enabler), firmware updates are a delicate matter. Despite the vague changelog, the homebrew and developer