So to update to 2.3 is almost same amount of work as to update to 2.6, so I've done the later. 2.6 wants newer gnutls, so updated to the last version to use the old ABI (luckily that's sufficient), which also wanted slightly newer gcrypt. That's all as far as dependencies go, and about things depending on wpa_supplicant I could only think of NetworkManager, and that still seems to work fine - wifi still connects and works.
So before I push out an update, please somebody test the wifi after doing "opkg install" on these packages, in the order given:
http://notaz.gp2x.de/tmp/ipk/libgcrypt11_1.4.6-r1.5_armv7a.ipk
http://notaz.gp2x.de/tmp/ipk/libgnutls26_2.12.24-r8.4.5_armv7a.ipk
http://notaz.gp2x.de/tmp/ipk/wpa-supplicant_2.6-r0.5_armv7a.ipk
Probably best to reboot after installing just to be sure old wpa_supplicant isn't running instead of the new one.