According to at least one Greyhawk wiki, the following Greyhawk adventures were adapted for 4e, either as free gameday stuff or as Dungeon articles:
Beyond the Crystal Cave
Hall of the Fire Giant King
Lowdown in Highport
Steading of the Hill Giant Chief
The Glacial Rift of the Frost Giant Jarl
The Hidden Shrine of Tamoachan
There was also a brand-new adventure, The Last Slave Lord, which was published in 2013 for 1e or 2e, but has conversion notes for 4e rules. It was designed to be slotted in after A0-A4 (Against the Slave Lords), rather than the separate A1-A4 list (Scourge of the Slave Lords).
I haven't seen any player-facing, rules-related content that is specific to Greyhawk in any of my other sources, so I don't think that side of things was done. There may be references to it in setting information, which wouldn't be included in the sources I use for checking for rules-related content.
Edit: I will, however, note that a few Greyhawk deities are included in the official Points of Light setting pantheon. Among them are Kord (a thematic favorite of mine from 4e), Nerull, and Pelor. The 4e pantheon in general is a blend of several different sources, drawing on Greyhawk, Forgotten Realms, Dragonlance, and (believe it or not!) outright Greek mythology. (Erathis is meant to be an Athena analogue, as a semi-belligerent goddess of law, skill, and civilization, while Bane is the Ares analogue, the god of warfare-as-slaughter but also a paragon of physical prowess and martial discipline, reflecting some of the influence of the Roman Mars.)
As with a lot of things in 4e, the default setting was intended as something of a convergence point. It's light enough on detail that you can plop most of its content into pretty much any setting without ultraspecific history that would conflict too much. Dark Sun and Eberron being two prime examples of "ultraspecific rules" that would conflict unless you heavily alter things.
Edit 2: Pardon, I forgot Tharizdun. Also, Wee Jas is often thought to be the inspiration for The Raven Queen, so that could be one more major (and now quite popular) deity from Greyhawk that got a 4e treatment, depending on what you believe.