As of 1:00 AM Central US time on 12/23/2012, the FTB Update Sheet Shows that all mods with world gen have been updated. This includes Xycraft, which I believe is still worldgen only at this point, and ExtraBees which is a DEV version. Computercraft and IC2 are still in beta as they were with the last FTB release.
Some mods on the update sheet are shown as not updated to 1.4.6, yet are shown as 1.4.6 on their MC forum pages. These include:
NEI_RedPowerPlugin
WR-CBE
This leaves the following mods not yet updated to 1.4.6 and some notes I have added about them
Equivalent Exchange 3 - basically in alpha, may actually be updated, but not ready for pack inclusion
GravityGun
Immibis Core - author on vacation till 27th of December
InvTweaks
Mystcraft - I believe author is on vacation or work related trip and will not be updating until after X-mas
NEIPlugins
TubeStuff - author on vacation till 27th of December
Inv Tweaks, Mystcraft, and NEIPlugins are the only mods in the current beta pack release. Mystcraft does not require worldgen except on its own created worlds and can be added at any time, however it does add item recipes and if absent will cause some problems in updating any worlds that have items created through the mod.
Inv Tweaks is client side and can be added at anytime although I admit I would miss it till added.
I believe NEIPlugins is also client side, but since it adds NEI functionality for several mods, is probably the one actual mod needed for release .
Of course, this info may have changed some while I have been writing.
Some mods on the update sheet are shown as not updated to 1.4.6, yet are shown as 1.4.6 on their MC forum pages. These include:
NEI_RedPowerPlugin
WR-CBE
This leaves the following mods not yet updated to 1.4.6 and some notes I have added about them
Equivalent Exchange 3 - basically in alpha, may actually be updated, but not ready for pack inclusion
GravityGun
Immibis Core - author on vacation till 27th of December
InvTweaks
Mystcraft - I believe author is on vacation or work related trip and will not be updating until after X-mas
NEIPlugins
TubeStuff - author on vacation till 27th of December
Inv Tweaks, Mystcraft, and NEIPlugins are the only mods in the current beta pack release. Mystcraft does not require worldgen except on its own created worlds and can be added at any time, however it does add item recipes and if absent will cause some problems in updating any worlds that have items created through the mod.
Inv Tweaks is client side and can be added at anytime although I admit I would miss it till added.
I believe NEIPlugins is also client side, but since it adds NEI functionality for several mods, is probably the one actual mod needed for release .
Of course, this info may have changed some while I have been writing.