Be cracked by software
Unlike the older iPhone, the 3G can't... yet. So meantime you probably need a SIM card adapter.
Easily sync with Google Apps
It can and it can't. The email works well, but synchronisation of calendars or contacts requires Nuevasync. Nuevasync is free, works well, and doesn't need to be trusted with any of your passwords.
Work nicely with push data
Yes, it will if you have a nice Exchange server, or if you use MobileMe. But using MobileMe with Google Applications isn't straightforward, and neither is migration between the two. Hopefully Google will introduce push support soon. Emoze offer a push service to sit on top of other email providers, but it's not a quick win.
Let you swap tasks
Surprisingly, you can't switch between applications. If you're browsing the web the web and need to dip into your contacts, the web browser gets closed. Fortunately when you re-open your browser it will remember where it was, but the process takes time and other applications don't work so well.
Include copy and paste
So you've been emailed a thirteen-digit tracking code for your Royal Mail parcel and want to track it online? You cannot copy the number from email and paste into your browser, and -- as above -- switching between the two involves closing the former. There is an application called iCopy which emulates copy and paste, but it involves sending your "clipboard" data in plaintext over the web. Top tip: carry around a notepad and pen with your iPhone 3G.
Whilst the scrolling is usually lag-free, there can be quite a delay loading applications. If you have a few hundred contacts, prepare to wait a few seconds before your iPhone starts responding when you press "Contacts".
Provide Open Source or free RDP and VNC support
It doesn't, not yet, though there are commercial implementations of both, and limited "free" versions of those.
Have native office applications
No, it doesn't have word processing, spreadsheets or presentations.
Have native chat applications
There are plenty of web based chat systems that work with or are built for the iPhone 3G. But do you want to put your chat account data into those systems? And remember, when you want to switch to another application on the iPhone, your web browser will be closed. MobileChat has been around for a while but it's not free and their servers have been falling over since launch.
Have a task list application
The best it'll do is get you into the iPhone version of RememberTheMilk. A native application would be preferable, as whilst the web solution looks lovely, parts are cryptic. After fifteen minutes of playing with it I think I can do everything apart from mark a task as completed.
There's no native client yet, so the office can wait.
Whilst there is a port of Nethack available for the iPhone 3G, the touchscreen interface doesn't allow for enough 1-touch commands. It's possible to play any of the games in a terminal through an SSH session, but there's still a problem.