I am replacing a Canon G-1 Powershot. Will my wide angle lens fit on this camera?

Is there an alternative to the Powershot that wopuld have a top hot-shoe for external flash?

Roger,

I assume your wide angle lens for the G1 is the WC-DC58, as that's the one Canon built especially for it. Unfortunately, Canon has opted to create a new wide angle lens for the S2 and S3 IS, designated WC-DC58A. They've similarly created new versions of the other two add-on lenses and the lens converter that's necessary to mount them.

These lenses seem very similar in purpose and result, but I wouldn't suggest a blind buy on the off chance they might fit. You may want to contact Canon's customer service to ask.

If you want a hot shoe for your flash, I'm afraid the only options in the Canon camp are the next models up the line from your own G1. All G-series models have the hot shoe, though your wide angle lens won't be good with any of them besides the G2. If you expand your range to encompass other brands, the Panasonic FZ20, FZ30, and FZ50 all feature hot shoes, and are relatively similar feature-wise to the S3 IS.