Can't launch minecraft after installing Inventory Tweaks. I've update Forge, Forge Mod Loader, (which doesn't have the version specified). I downloaded the most recent, non-developer version on Inventory-Tweaks from your website. It should also be noted that the version of FML specified in the error message doesn't appear to have been released yet.

I've heard nothing but good things about Inventory-Tweaks and am very disappointed I haven't been able to get it to run yet.

Try the latest version of Forge. Their version numbers are a bit confusing.