Wow, this would be a fantastic lens to pair with a 7D for dimly-lit indoor sports. Sort of the poor man's crop version of a 1D + 70-200mm f/2.8 combination.A 2.0 zoom won't be a poor man's anything. This thing will be large and heavy and expensive. If it's an L, it'll surely cost $2k or more. If it's EF-S, it'll easily be the most expensive EF-S available. If it's a Cinema lens I'll stomp and curse and spit.
Obviously it would be quite large and quite pricey, but unless it's a Cinema lens a 7D + 55-110 f/2 would still be considerably cheaper than a 1D + 70-200mm f/2.8.