Now I live in the Philly area and this is the first that I have heard of a blog tax! It seems that no matter what amount of money you earn - even if it is as low as 50 cents you still have to pay a tax on it! It's called a "Business Priviledge Tax" - is this aggravating or what!
Good! Maybe it'll drive some of the meaningless drivel off the web! :)
On the other hand, business licenses/fees/etc are nothing new. Putting ads on a site is a clear indication of the intent to make money. Many new businesses take years to become profitable, all the while paying substantial business expenses. This is just anoter expense.
The $300 is a lifetime fee, not annual. The annual fee is just $50. While I'm not a fan of ANY taxes or government "fees", including this one, I don't consider it a "blog tax" like some do.
If you are making money on a website, whether it's through ad clicks, selling links, affiliate referrals, etc. you're running a business. The $50 fee for this is less than the cost of incorporating, and you have to pay taxes on the income you make anyway whether you're considering yourself a business or not.