RIM should bring it back. look at the new curve 9220; it has a dedicated bbm button smack dab in the middle of where my beloved LSCK used to be. it shouldn't be that difficult.
if they cant do that then the should mae all new bbs with a dedicated bbm button... and make it reprogramable.
who else misses the ol' left side button? who else thinks it deserve the same fate as the scroll wheel?