All the information you need can be found right here. BTW: the packs that use Minecraft 1.5.2 are currently private packs (they aren't automatically added to the launcher and require a code to access; however, the codes are public knowledge.) You must enter the private pack code on the launcher to be able to use them by clicking Private Packs, inputting the pack code and clicking Add. For Unhinged and Unleashed, codes are FTBUnhinged and FTBUnleashed respectively; the 1.5.2 beta packs are 152wgt (for the GregTech version) and 152ngt (for the DartCraft version); Direwolf20's 1.5.2 pack is Direwolf20_1_5.
BTW, to make a long story short, all FTB packs are currently "locked" except for Unhinged, Unleashed and Direwolf20 1.5, so there won't be any more updates to any packs except those, at least not in the foreseeable future.