we try to get the OpenWRT firmware working on the Siemens SE505 router revision 2, but facing a few remaining problems. By testing the experimental build the router was continuously crashing in the diag.o module and rebooting.
Please see: http://openwrt.org/forum/viewtopic.php?id=965 for details.
Uncommenting out the module in the preinit script is a workaround at the moment. Do you think there is a chance to fix the problem and promote it to the actual build? Would be very nice to get the firmware running on the newer version of SE505 too....