Re: samsung blackjack-
I switched from Treo 650 to Windows Mobile (Cingular 3125) flip phone and have now moved to BB Pearl.
After using Treo for 2 years I now have very little appetite for bulky smartphones. BB 8700 series and 8800 fail on that count. Windows mobile phone that I used had a fantastic form factor (RAZR like flip design) and availability of all kinds of Windows software, but it did not natively handle blackberry email, thus the latest switch to Pearl.
BB Pearl actually looks like a phone with fantastic form factor. It is small and provides all the functionalities I need in my phone. Great email interface, very high quality phone, a passable camera (with flash), full Bluetooth and very nice Outlook (addresses/calendar/etc) integration. Best of all it supports BB email natively and that is a big advantage for me.
Samsung Blackjack looks nice (ads certainly look nifty) but it has a big form factor, and I am not sure it supports BB Enterprise server natively or not. I know a BB solution for Windows Mobile is on its way, but if your organization is on BB, I'd suggest you stick to BB. Goodlink and other indirect methods are not all that.