Just to let every one know Thaumcraft updated to 4.1 today, and we had been including the API in our jar when we did not need to do. When Thaumcraft 4.1 updated it's API, which we were accidentally overwriting due to not forcefully loading after Thaumcraft, as it would have lead to an infinite loop with Forestry. Anyways, just re-download 3.15.3 and you will be good to go again. (I really need to talk with Scott to so that we can update our Thaumcraft calls so we don't need to include the classes in our work space like he did with the old IC2 API.)
Download EbXL 3.15.3
As for the 1.7 update, it is coming along and with the new block loading code adding the Quarter Logs (which are being renamed to Corner Logs in order to support larger trees in the future) was rather trivial. Even with having to rename the textures to match the new naming convention, converting the last four logs only took about 2 minutes to get them added and in the game. One thing that I like about the new block id system in 1.7, is that blocks will appear in the order that they are created now since MC automatically assigns their internal numerical id's, meaning that we can control the order that blocks are sorted in our creative tabs with nothing more than changing the order of the blocks in the config file. Talk about convenience.
On a 1.6.4 to 1.7.x transition note one of the upcoming 1.6.4 releases will be generating a ton of ID mismatch messages, as the way that we currently register blocks/items is a little troublesome and is not user friendly. As long as you do NOT delete your config file this will not break you world, it should just make updating to 1.7.x possible without breaking everything. However, the 1.7 version will probably have some new biomes, so you are going to get issues with chunk borders, if added to an existing world, so that should not be any more of an issue than it would be otherwise.
I still would recommend creating a new world in 1.7 though as it chunk borders are ugly, and time willing we may have an enhanced world type in 1.7. (Which would most likely make it EbXL 4, but that is not confirmed at the moment.)