18th February 2004 - RS1 and RS2 friendlists linked
Today, we have successfully linked the rs1 & rs2 friend lists together.
This means whilst playing rs1 you can now talk to your friends playing rs2, and vice-versa!
Also please note that from now on (as of yesterday in fact) any friends you add or remove from your friends-list in either game will instantly affect the other game too. This is because both games are now running from the same list.
Taken from Runescape.com