If you are thinking for more of a business phone and are wanting functionality, size, power, and durability, then get the Blackberry or IMO the Treo. If it is more for leisure then get the Iphone or if you have TMobile then hands down the G-phone (google's phone). I am not saying Iphone can't do all of the business things, but why have all the bells and whistles if you don't plan on using them that much, the BB can do all of the impt things. The Iphone and G-phone are about the same damn thing, there are plenty of articles that explain their differences, but IMO they are both badass. All of my friends including myself have all recently gotten these types of phones ranging from blackberry, blackberry pearl, Iphone, blackberry storm, the Bold or Behold or whatever the hell it is, and my girlfriend is checking out the G-phone. Everyone one of the people that have anything but the Iphone will tell you that if it wasn't for the SP they would have gotten the Iphone.
The only things I do not like about it is the fact that you can't text sideways like you can when you type on the web, you can't send pictures via picturemail you have to send it via email, no video camera, and the 3G isn't that "large." I drop calls and only get 3G in big cities and usually won't even pick up the Edge network at home in KY, but its nice in a college town because everyone has WiFi and most restaurants and places of that nature will let you use it. I also don't like that if a site is using a plugin or java or something of that nature then you can't view the site due to the inability to DL the program. However, there is supposed to be a software and a hardware update sometime this summer, so if you are on the fence about getting one then you might want to wait and see what the new one will look like and if you have the 3G iphone the you will be able to get the software/data update for free. I have heard that you will be able to send pictures via picturemail, text sideways, video conferencing, and a lot of other things. Another little thing they neglect to advertise is the warranty policy. You have a 90 limited warranty on the iphone along with apple tech support (since apple is the only people that can give you tech support, not your phone store) After that 90 days it costs you something like $50+ just to call apple and ask them a question, much less if anything has to be fixed. You CAN buy an ext warranty anytime within the first 90 days for 70$ that extends the phone warranty and tech support to 2 yrs I believe, but don't quote me on any of that.
Yes the battery life is not great, but I was used to charging every phone I have ever had everynight so that hasn't bothered me. It has frozen on me before but you can reset it quickly, keep in mind its a freaking computer so sometimes it will freeze. If you get one you will get frustrated sometimes but if you catch yourself without the Iphone (or BB, treo, gphone, storm, etc) you will wonder how you did without it.
ps. call an apple store and tell them what type of email server your company uses and they will be able to tell you, or I am sure it can be found on google.