They probbably will work. I haven't tested it, but my shoutbox hack (created on Beta 4, then updated on Gamma, RC2, and RC3) will probably work on vB3 Gamma and above, and I bet some of my smaller hacks will work on vB3 Beta 3 and above (although no one should be running that old of a version

) Most of the time, when a hack is made on a certain version, it will also work on some of the past and future versions.