2008-April 420 came late this year :o
Polycom SIP Firmware 3.0 Polycom are by far the biggest Nazis when it comes to their firmware. They publicly release old versions but refuse to release the newest version unless you do some sort of silly sign up and I don't mean fill out a form and create an account in 30 seconds. You need to be a "Certified reseller." Well now thanks to this site you can be a "certified downloader." I also suspect they are using GPL code without releasing the firmware but I'm not certain either. So here is the 3.0.1 firmware 
SPC Utility for SPA phones. The SPA phones 94x and 92x both use the same firmware, and configuration files. Download here (v4.1.15, Linux and Windows)
I have verified this works with Linksys SPA921 up to fw 5.1.5, SPA922 up to fw 5.1.5
SPA-9x1 SPC Linux and Windows for f/w 5.1.5 Download
SPA-9x2 SPC Linux and Windows for f/w 5.1.7 Download
SPC Utility for SPA ATA. While I have not done extensive testing, I believe that all the PAP2/SPA phone adapter (perhaps except for the PAP2 v2 & PAP2T) All use SIMILAR (NOT THE SAME) firmware and the same configuration files. Download here (v3.1.3, Linux) v2.0.11(e), Windows
I have verified the Linux version working with Sipura/SPA-3000 up to fw 3.1.10(GWd), PAP2-NA up to 3.1.10-ls. Does not work with SPA2102 (tested 5.1.9 fw)
Each utillity will generate sample configuration files for the target device. The firmware can be downloaded from linksys.com or sipura.com, they do not impose their draconian requirements on these for some reason (at least for now).
SPA Phone Admin guide. Explains the configuration parameters for the SPA phones.
Download Original Sipura Guide
New Linksys Guide SPA9xx v3.01
SPA-ATA provision Guide. Basic overview for provisioning of PAP2/SPA-ATA. Download here (PDF) SPA-2000 PDF
WIP-300 Auto Provision WIP-300 WiFi phone provisioning. This phone was OEM'd by Linksys. The ODM is Wistron NeWeb who also makes the GSM/WiFi phones for Prellii, Dlink and also the Dlink and 3com WiFi phones. Download here (Windows only)
This website is released under PUBLIC DOMAIN. The author makes absolutly no claim to ownership of any content on this site and further disclaims that the content here is posted for interoperability of Linksys and Sipira SIP devices only. ABSOLUTLY NO WARRANTY, EXPRESS OR IMPLIED IS PROVIDED FOR ANY FILE APPLICATION OR ANY CONTENT OTHERWISE HEREIN. THESE FILES MIGHT CAUSE DAMAGE TO YOUR DEVICES, DEATH AND/OR THERMONUCLEAR REACTIONS AND/OR OTHER UNEXPECTED BEHAVIOR. USE AT YOUR OWN RISK.
Linksys: Stop being such dickheads about giving this shit out