I haven't heard about these tax rises nor have I checked myself but I'm happy to take you word and signed up.
I've signed a fair few of these petitions, I wonder if they do any good. When a few million people marched in London in protest against the imminant invasion of Iraq the government just seemed to ignore it and go along with the US anyway. Be interesting to see a response from the goverment stating which petitions have prompted new research or legislation or anything really. The No 10 web site sometimes responds to petitions, but all the responses I've read just simply re-state the status quo, it's like talking to a brick wall.
If this tax rise proposal is true, it would be cool if a mass ride out was organised in London to bring the place to a stand still. Even if the government didn't listen it would be cool riding with so many other people and bring some publicity to the situation 
Oh I also read in MCN that Ken Livingstone was against bieks using bus lands in London but Boris Johnson was all for it, I wonder if anything will come of this. If it's implemented in London I would have thought other cities will follow suit 