I'm constantly amazed how seldom the issue of shutter lag comes up in these fora, whether we're talking about the latest Canon P&S offerings, or stuff that came down the pike over 12 months ago (like the Panasonic LX3). In the case of the S90 (the only new Canon Powershot that genuinely interests me) people seem to be infinitely more concerned with "deal breakers" such as size and pocketability, the lack of zoom range, the lack of an optical viewfinder, the lack of a grip, the power of the onboard flash, the control rings, etc., etc.
For example, just look how little interest there's been in responding to this particular thread.
And yet, the amount of shutter lag should be of paramount concern for any street photographer looking to adapt one of these point and shoot cameras for stealth photography. So far--and I'm willing to be corrected if you have other information--it seems to me that of all the manufacturers of sub-MFT sensor, full feature cameras (viz, Ricoh GX series, Panny LX3, Canon G series, and perhaps Fuji--of which I have little personal knowledge) only Ricoh has made any serious attempt to address this problem. Even the magnificent LX3, which I use with great frequency for travel and for my daily work as a newspaper shooter, falls down quite miserably in the area of shutter lag. The little Panny performed brilliantly and dependably during a recent month-long trip through Peru--except when I attempted to shoot fast moving targets like running, jumping, gesticulating folk dancers and musicians, or scurrying street demonstrators.
I'm thinking that IF S90 image quality and noise suppression turn out to be everything Canon is claiming, and IF Canon has made genuine advances in pre-focus shutter lag times, the S90, with its ingenious control ring system, 28mm f/2 lens and slightly extended telephoto range (not much over the LX3's 60mm, I'll grant you, but still plenty for me at 105mm) might just be an excellent adjunct to my LX3, with which I have no intention of parting.at this time.
Occasionally, I still shoot with the highly pocketable 7.1 MP Canon SD 800 IS Elph I bought several years ago. Reason: I've discovered it's capable of capturing perfectly timed (non-flash) daylight shots of martial arts competitions or of dance performances under decent illumination. Is it too much, then, to hope that, more than three years down the road, Canon has at last opted to produce a 10 MP, RAW-capable point and shooter that features pre-focus shutter lag times equal to or less than those of my SD 800 IS?
So I'm keeping my fingers crossed that the S90 will lend itself admirably to aperture priority, hyperfocal distance shooting, and that prefocus shutter lag times will at last reduce the frustration of trying to capture the movement of an arm, or the toss of a ball, or the leap of a dancer.