Although the recent advent of more affordable, entry level dSLR cameras has narrowed the gap for users wanting to step-up from snapshot models, it can still be a bit of a learning curve.
And if you haven't already, you may also want to look at our dSLR superguide: The section on "What do you want to shoot?" offers tips on what features you should look for in different situations, including "street" photography.
You'll probably want to consider a more lightweight model if you'll be carrying it around everywhere. Likewise, if shooting a broad range of subjects, a twin lens kit or similar (usually a wide-angle and telephoto) will give you versatility.
Our reviews all state the body-only price of each camera so don't forget to factor in the cost of accessories, such as memory, extra lenses, a tripod, etc.
If you're keen on getting the "latest and greatest", you should be aware that Feb/March is usually the time when camera manufacturers announce new models.