I have this same issue let me know how I can help.  

IBM ThinkPad T42 2374-Y1E
#rpm -qa | egrep 'ipw|kernel'
kernel-2.6.9-1.724_FC3
ipw2200-firmware-2.2-5.at
ipw2200-0.19-19.rhfc3.at
ipw2200-kmdl-2.6.9-1.724_FC3-0.19-19.rhfc3.at

Error for wireless request "Set Bit Rate" (8B20) :
    SET failed on device eth1. ; Operation not supported.

Mine works from boot up.  If I make any on the fly changes nothing works.  

I was running 0.16 with no errors but upgraded to 0.19 when the new FC3 kernel
came out.
Thanks,
Mike (mrdvt92)

I have experienced this problem as well, under v0.21.

"iwlist eth1 scan" works just fine.  So does "iwconfig eth1 essid XXX" 
and "iwconfig eth1 channel XX"

However, any attempt to use "iwconfig eth1 rate XXX" returns the error listed 
in comment #1.  The specific commands I have tried are:

iwconfig eth1 rate 54M
iwconfig eth1 rate 11M
iwconfig eth1 rate auto

*** Bug 559 has been marked as a duplicate of this bug. ***

Bug #559 has a patch for this.

After spending more than a week trying (unsuccessfully) to get this up and 
running, I took the drastic step of completely reinstalling FC3.

After the reinstall (and a kernel update to .741_FC3), I tried again and the 
card started working flawlessly.

I am still getting the error message, but it DEFINITELY DOES NOT affect 
whether or not you can connect.  So I guess the true nature of this bug is the 
displaying of an erroneous error message under FC3.  I have observed it under 
versions .19, .21, and 1.0.  I haven't tried earlier versions.

Mike, Mark, could you try ipw2200 1.0.1 to see whether you still get the error 
messages?

I no longer get the datarate error from /usr/bin/system-config-network.

kernel-2.6.10-1.770_FC3
ipw2200-1.0.1-24.rhfc3.at
ipw2200-firmware-2.2-5.at
ipw2200-kmdl-2.6.10-1.770_FC3-1.0.1-24.rhfc3.at

>dmesg
ieee80211_crypt: unregistered algorithm 'NULL' (deinit)
ieee80211_crypt: registered algorithm 'NULL'
ipw2200: Intel(R) PRO/Wireless 2200/2915 Network Driver, 1.0.1
ipw2200: Copyright(c) 2003-2004 Intel Corporation
ACPI: PCI interrupt 0000:02:02.0[A] -> GSI 11 (level, low) -> IRQ 11
ipw2200: Detected Intel PRO/Wireless 2200BG Network Connection
divert: allocating divert_blk for eth1
ipw2200: Firmware error detected.  Restarting.
ipw2200: Firmware error detected.  Restarting.

Mike (mrdvt92)

the patch that supports date rate setting was already added in the driver.

so changed to fixed!

The bug is verified by submitter.