I've received some reports that people weren't able to create the foundation-pitch tag to post under, so I created a post with this tag (namely, this one). New posts should be able to use the tag by specifying in the new post UI as follows:
I think this tag is completely redundant and you should use #foundation instead. This just creates more fragmentation of the forums because a) we already have #evolution:pitches#server:pitches sub-categories for pitches, b) we left the [pitch] title prefixes behind and finally c) in other categories you probably won't be pitching anything but rather work on a specific feature or ask question about it, so it shouldn't be #foundation-pitch there either. If nothing else, we should make another sub-category for corelib pitches.