I think this is because the module doesn't compile with 2.6.31, I get this:

michael@michi-sl300:~/linux-kram/lenovo-sl-laptop$ LC_ALL=C make
make -C /lib/modules/2.6.31-2-generic/build M=/home/michael/linux-kram/lenovo-sl-laptop modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.31-2-generic'
  CC [M]  /home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.o
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_get_radiosw':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:227: error: 'RFKILL_STATE_HARD_BLOCKED' undeclared (first use in this function)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:227: error: (Each undeclared identifier is reported only once
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:227: error: for each function it appears in.)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:233: error: 'RFKILL_STATE_UNBLOCKED' undeclared (first use in this function)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:233: error: 'RFKILL_STATE_SOFT_BLOCKED' undeclared (first use in this function)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_update_rfk':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:246: error: implicit declaration of function 'rfkill_force_state'
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_enable_show':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:291: error: 'RFKILL_STATE_UNBLOCKED' undeclared (first use in this function)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: At top level:
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:322: warning: 'enum rfkill_state' declared inside parameter list
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:322: warning: its scope is only this definition or declaration, which is probably not what you want
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_rfk_get':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:329: error: dereferencing pointer to incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: At top level:
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:333: warning: 'enum rfkill_state' declared inside parameter list
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:333: error: parameter 2 ('state') has incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_rfk_set':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:335: error: 'RFKILL_STATE_UNBLOCKED' undeclared (first use in this function)
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: At top level:
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:342: warning: 'enum rfkill_state' declared inside parameter list
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:343: warning: 'enum rfkill_state' declared inside parameter list
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'lensl_new_rfkill':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:346: error: storage size of 'initial_state' isn't known
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:348: error: implicit declaration of function 'rfkill_allocate'
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:348: warning: assignment makes pointer from integer without a cast
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:355: error: dereferencing pointer to incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:356: error: dereferencing pointer to incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:357: error: dereferencing pointer to incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:360: error: dereferencing pointer to incomplete type
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:367: error: implicit declaration of function 'rfkill_free'
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:346: warning: unused variable 'initial_state'
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c: In function 'bluetooth_init':
/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.c:410: warning: passing argument 6 of 'lensl_new_rfkill' from incompatible pointer type
make[2]: *** [/home/michael/linux-kram/lenovo-sl-laptop/lenovo-sl-laptop.o] Error 1
make[1]: *** [_module_/home/michael/linux-kram/lenovo-sl-laptop] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.31-2-generic'
make: *** [all] Error 2

Does anyone know how to fix this?