Jonathan Dieter has just made F16 and F17 Koji builds for the multithreaded yum-presto (currently only in F18 and Rawhide) which takes advantage of multiple cores. Since applydeltarpm maxes out the CPU, they will probably give a linear speedup. He doesn't plan to ever put the F16 version into updates-testing but might do it for F17 if it gets positive feedback. (I personally don't have multicore hardware so can only test for good behavior, not for the speedup.)
https://bugzilla.redhat.com/show_bug.cgi?id=701711#c10
http://koji.fedoraproject.org/koji/buildinfo?buildID=359518 (yum-presto-0.9.0-1.fc16)
http://koji.fedoraproject.org/koji/buildinfo?buildID=359516 (um-presto-0.9.0-1.fc17)