I am searching the last SDK for the iPhone OS 2.2.1 (last in the 2.x series) for Mac OS X 10.5 Leopard.
The exact name of the DMG image is: "iphone_sdk_for_iphone_os_2.2.19m2621afinal.dmg"
(md5: 9d0a818f41be507537495920cd0ef9bc, size: 1.75 GB)
The old link at Apple's Developer site is not working anymore and I cannot find any working links or torrents of it. (Unfortunately, Apple deleted most of the old developer stuff lately
)
The reason why I am searching this, is that I have just learned about the possibility to getting this SDK to run on a PPC-based Mac under Mac OS X 10.5 Leopard. According to the articles, linked below, it is possible to develop, debug and deploy Apps for IPhone OS 2.x because Apple compiled the whole toolset as Universal applications (x86, ppc), including the iPhone Simulator !!
Articles how to use iPhone 2.x SDK on PPC Macs:
Screenshot iPhone simulator running on a G4 Mac
How to install iPhone SDK 2.2 on PPC with editing install script
How to install iPhone SDK 2.2 on PPC using Pacifist
Installation with little custom user script
Article with step-by-step instructions and many screenshots
According to this article the installation on PPC Macs works up to SDK version 2.2.1, SDK 3.0 and higher not working since compiled for Intel architecture only
Installation procedure with full editing listings
installation procedure with screenshot of iPhone simulator and provided file with above listing
I know this is a little out of the scope of the Macintosh Garden website.
But it is abandonware too, since not available and supported by Apple anymore.
If anyone has still the DMG image and could provide me a copy, it would be very happy ! 
P.S.:
I am searching too the last SDK for iPhone OS 1.1.5 (last in the 1.x series):
According Wikipedia first and only SDK for iPhone OS 1.x was:
iOS 1.2b1 Beta 1 (Build 5A147p), released on June 29, 2007, announced at an Apple Hall meeting.

Try these...