With the release of Android 2.1 SDK it is possible to play with Google's support for Exchange ActiveSync which is included with the SDK emulator package.
It is important to note that just because the build of Android supports it, it is down to individual device manufacturers as to whether they choose to implement Exchange support - presumably due to licensing costs - and they may develop their own client software.
This post is for general geek interest only.

HTC Android-based devices already feature their own Exchange client developed by HTC independently.

For instructions on how to configure the SDK read this article - http://blog.brightpointuk.co.uk/google-release-version-20-android-sdk

Setting up the Exchange Account

Launching the Email application for the first time will prompt you what type of email account you want to configure:

Selecting Exchange will prompt you to enter all of the settings that an Exchange ActiveSync client will do, ie Username, Password and Server Address:

If you are using a self-signed SSL certificate (ie not root-trusted) on the Exchange server, you will need to select the option to Accept all SSL certificates. I did try manually installing the root cert for an Exchange server that uses a self-signed certificate and unticking this option, and received this error:

So at the time of writing it looks like you have to accept all certificates to use a self-signed cert.

Once you have entered all of the connection settings you can then specify how you want mail delivered, and how much:

On this screen you can also specify which other PIM folders you want to synchronise. You will notice a lack of the ability to sync Calendar information in this emulator release.
On the next screen you can enter a name for the account as well your sending name:

Providing all went according to plan, your mail now will now be delivered to the device:

Mailbox subfolders are also supported:

The device will appear to Exchange as simply 'Android':

Editing the account settings allows you to adjust your initial choices should you desire:

For an overview of the Exchange ActiveSync client available on the HTC Desire, read this article - http://blog.brightpointuk.co.uk/introducing-htc-desire

For information on accessing your GMail via Exchange ActiveSync rather than IMAP read this article - http://blog.brightpointuk.co.uk/access-google-premier-apps-email-android...