Automatic hashtags in replies to hashtagged tweets

If a tweet has a hashtag, it would be nice for that hashtag to be typed in for you when you hit reply. This would effectively keep a conversation thread alive with the minimum effort from the user.

Example:
usera says: I'm at #FOWA

userb says: @usera #FOWA How are the hot dogs?

It would be nice for userb to only have to type "How are the hot dogs?" rather than the whole thing.

You could even have a hash reply button that replies just by taking the hashtags without the @ reply.

Example:

usera says: I'm at #FOWA

userb says: #FOWA Anyone fancy a tweet up?

userb would just have to hit the hash button and type "Anyone fancy a tweet up?"

Hope this makes sense!