I ran into this issue about two weeks ago, but didn’t get through to writing about it.

The new (Debian) Kernel 2.6.24-1-amd64 no comes with ‘built in’ drivers and firmware for various Ralink WIFI devices. E.g. there are drivers for both PCI and USB devices (rt2×00 chipsets, including rt2500 (pci), rt2400) from rt2×00.serialmonkey.com compiled as modules into the kernel.
Unfortunately, those drivers really didn’t work out for me. My WIFI PCI Card has got a Ralink rt2500 chipset. I used to compile the module myself, using the rt2500 drivers from rt2×00.serialmonke.com CVS.
But with kernel 2.6.24-1 various modules, such as rt2×00, rt2×00pci, rt2500, rt2500pci, were loaded automatically. But the result wasn’t what I had hoped for. Even though my WIFI card was recognized immediately and connecting to my WIFI was really easy, because of the new GNOME network manager that includes WIFI connections, the transferrate always went down to 1 Mbit/s.

I could not manage to get it faster.

So the conclusion, I built the kernel again, manually, without any WIFI support included. Then I used those nice rt2500 CVS drivers from serialmonkeys.org and all works fine again :)

Currently I’m spending my very rare free time (I’m pretty busy with school right now) on getting my gentoo installation to work properly ;)

Edit: (Thanks adlerweb): Yeah I know I could’ve blacklisted the built-in modules, but I was in the mood (and found some time ;) ) for some ‘handicrafts’