This last weekend saw the switch off of Sunsolve and the migration of the old Sun support system across to Oracle's My Oracle Support. Unfortunately, one of the things lost was the incredible ease to locate and download patch clusters. Oracle doesn't seem to offer such an easy method, probably due to their historical reliance on CPU patches.
All is not lost though, you can still download the patch clusters and individual patches and here's how.
Log into My Oracle Support - you will need to have pre-associated your username with a valid contract and CSI. Once logged in go to the "Patches & Updates" tab (1) and then search for the desired patch in the "Patch Search" box (2) on the right:
Update (30 Jan '11): As Peter points out in the comments, the search tool does an EXACT match. So you could search for 123456-07 to find exactly this version of the patch. If you don't know the newest version, you have to add the "%"-wildcard to find all versions: 123456-%
Downloading the patch clusters is a bit more of a challenge.
Log into My Oracle Support, go to the "Patches & Updates" tab (1), select the "Product or Family (Advanced Search)" (3) link in the right search box, and then fill in the rest of the search criteria:
... then click "Search". This will take you to a new page and after a short period of time, a long list of patches will appear, including the patch clusters:
To speed up locating the patch clusters, you can then click the "Size" column on the right to order by size in reverse order and the patch clusters will appear at the top of the list.
I'm still trying to find out if there will be a replacement for the immensely useful PatchFinder tool.