Just look at this spreadsheet: https://docs.google.com/spreadsheet/ccc?key=0AsuKLj6RIQ8idFR3cFoxVXQzYVU4U3NLSVF5MnBGUEEThe central mods permissions topic is for mods that the FTB team have permissions for. These permissions DO NOT cover private mod packs so people who want to set up a pack, when we can, will have to go get permission for something the FTB team could have covered by getting permission for ANY modpack that is distributed through the FTB launcher. Especially, since the FTB team has to approve your private mod pack AND you have to provide permission for mods not in that pack.
In essence ANY mod already in an FTB Official pack should have been covered so people don't have to bombard mod authors with hundreds of requests to add their mod to one's private pack. Would you rather them spend time posting yes you can or no you can't or spending time developing the mods we all love or, better yet, taking a break from modding to spend time with loved ones so they can come back to developing fresh and ready to make the magic!!
Almost all of the mods on that list can be included in your FTB private pack with minimal hassle, by just providing credits as required and showing the FTB team that spreadsheet.
Any mod which isn't on that list, many will state on their topic that private modpacks are allowed. Others, just send them a PM stating you're making a private pack for your private MC server and I'm sure they'll say yes.