I suspect my digital camera needs are somewhat different than most better photographers on this site. Shirt pocket-ability with optical finder is foremost with me with just the small point and shoot variety so always have camera with me at airports.
I wear prescription dark sunglasses and outdoors can't well see the digital camera LCD viewers. I don't want to lug around a camera bag with the accessories, lenses, flash, light meters, etc. I have all that with my film aperature-preferred macro SLR two body outfit from 1970s technology with wide angle and zoom telephoto extra lenses which just doesn't get use any more.
My "old" HP 607 pocket digital has taken 13,600+ photois without fail in 35 months (I also upload on a different non-aviation website) and has recently developed a round slight "dark" spot in lower center of frame seen in sky shots of flying aircraft. Yes, even pocket digital cameras with fixed lenses can get dust or dirt on the sensor.
I just started using my new Canon PowerShot A720 IS with image stabilization, 8.0 mega pixels and all-important for me optical finder. This camera received a Best Buy Compact rating from Consumer Reports magazine in their July 2008 issue. It has double the range of the HP 607, having equivalent 35 to 210 mm range. It can take a Canon teleconverter lens with additional 1.7X range. And yes, it easily fits my shirt pocket. My first airport use of it was on 16 July 2008 at SZP and CMA. So far, I am impressed with it! I'll take it to OSH this year with its rechargeable batteries and small charger. Have a room reservation with 120 V AC power, not a tent camp under the wing like many visitors.