New ultra-compact digital camera?

I went to a digital camera talk this morning and got to play with some new camera's from Glazer's. There are some amazing ultra-compact cameras available now. I am very tempted to purchase one to supplement my nicer Nikon with something small enough to carry with me 24/7. I'm looking around and so far the top contender is the the Casio Exilim EX Z40 / Z50 / Z55. Other possibilities are Pentax Optio S5i or the Canon Powershot SD300. The Casio EX Z50 and Pentax Optio S5i are nearly identical physically and appear to use the same Pentax lens. My guess is that Casio and Pentax made this together and are each selling a slightly modified version of it. DP Review stats on the Optio S51 and the Exilim EX-Z55 indicate that the Pentax is superior in all ways but the LCD size and battery life. Admittedly the differences are small. Check out the features side-by-side on DPReview.com.