When I start rxvt and switch keyboard into the Cyrillic mode (I am using Xkb, it generate Cyrillic_* keysyms) and start typing, rxvt would not react (as if nothing is typed). When xterm, Netscape or gvim is started from the same shell, cyrillics works fine. I had the same problem in RedHat 5.1 In RH 5.2 I checked it with the following setup: glibc-2.0.7-29 rxvt-2.4.7-2 XFree86-libs-3.3.2.3-25 XFree86-3.3.3-1 XFree86-SVGA-3.3.3-1 P.S. nxterm has the same problem (I am going to report it as a separate bug) and as a result, I can only use xterm.
The problem still exists when using XFree*3.3.3.1-1
When I rebuilt rxvt-2.6.PRE2-1.src.rpm (from RawHide) on an RedHat-5.2 system (with all updates, including XFree86*-3.3.3.1-1), I did not have any locale problems. I can not test rxvt-2.6.PRE2-1.i386.rpm from RawHide since I do not have access to glibc-2.1 machine