If you use Gmail on a Mac, you should definitely know about Mailplane. It's basically a really fancy site-specific browser for Gmail, getting Gmail out of your browser tab and adding a lot of features you'd demand in a desktop email client. You can drag and drop attachments and sign in multiple accounts at once, just to name a couple. Plus, a release candidate for Mailplane 2.0 just came out, and it adds 37 new features.

You can do anything in Mailplane that you can do in Gmail, including the new video chat feature. The new gmail themes are also supported, and you can add your own custom stylesheet. It feels strange to use Gmail in a browser again after playing with Mailplane. Customizable keyboard shortcuts, dragging and dropping, and iPhoto integration are just a few of the handy features that make Mailplane a joy to use. It also supports one of my personal favorite things, Growl notifications

While many people using Google Apps are already happy users of the "new" version of Gmail (apparently Google doesn't want to call it Gmail 2.0), there are still many users of Google Apps that are stuck on the older version. If you're frustrated at seeing the cool new things you can do in the new Gmail and you're still stuck on the old version, there may be something that you can do.

If you are the administrator for your Google Apps account, or can talk to that person, there is an option under Domain Settings (General tab) in the Control Panel section called "Turn on new application features to my domain before they are rolled out to all Google Apps customers." A week after we checked that box on our Google Apps account, Gmail magically transformed to the new version. Good luck!

As more and more users start seeing the new version of Gmail, they're finding that their favorite Firefox add-ons and Greasemonkey extensions may no longer be working. One of the most popular Greasemonkey extensions for Gmail has to be Macros, created by Google employee Mihai Parparita. Luckily, a new version has now been released.

Those of you that are aware of the Macros script for Gmail have probably already all left to go grab the latest version. The rest of you still reading are probably wondering what all the hubbub is about, so here's a quick rundown of what Macros is, and why you need it.

Macros is a Greasemonkey script that adds a bunch of very useful keyboard shortcuts to Google's already very keyboard-centric Gmail control mechanism, like the ability to jump directly to a label by typing "L" then the label's name. While that's some pretty sweet functionality, Macros is worth installing for one specific shortcut: the D (for dismiss) key.

If you check the box for a few unread emails in your inbox that you know you don't need to read, you can press the D key to dismiss those messages. This will automatically mark them all as read and archive them in one fell swoop. It's amazing how fast you can process your inbox by first making a pass through and dismissing anything that is not relevant or necessary. This is a favorite trick for when you're returning from vacation or even on a Monday morning with a weekend's worth of messages piled up.

If you're not interested in installing Greasemonkey to get this functionality, consider just grabbing Lifehacker's Better Gmail Firefox add-on, which has Macros built right in, as well as a number of other useful features.

It might be a good idea to scrutinize your Gmail account more closely than usual these days. Not only is Google in the process of rolling out IMAP support, but it looks like some users are able to access a new version of Gmail. If you notice a new option that says "older version" or "newer version" at the upper right-hand corner, you're probably in. It should be right between the "settings" and "help" tabs.

Google Blogoscoped has a series of sreenshots showing some of the differences. Gmail 2.0 reportedly loads faster, although it's a bit early to say how much faster. And there's a much more detailed contacts section. There's a new contacts manager and the option to add images for contacts directly from Picasa Web. There also appears to be an option to "filter messages like these" from the Gmail "More Actions" drop down box.

If your account has the new interface, please let us know in the comments if you've noticed any other differences.