Continue reading for the details on just what Mailplane is about, and be sure to check out our screenshot gallery for a taste of how well (so far) Gmail and the desktop are getting along.
Unlike that browser just for Gmail, Mailplane wraps Gmail's web interface in Mac OS X software which allows it to do some really slick stuff. Upon opening Mailplane for the first time, it prompts you to set Mailplane as the default email app which allows you to click on just about any email address or 'mailto' link from the web to create a new Gmail message in Mailplane. If you also opt to install the iPhoto plugin, the Email button in Apple's darling iLife app will send your re-sized copies to Mailplane and attach them to a new message as well.
Dragging and dropping one or more files onto the Mailplane window also creates a new message with those files attached. Mail.app, your days are numbered.
Helping users to manage attachments coming into Gmail, Mailplane has a Downloads menu that can quickly take you to the default location for downloading attachments (set in a Preferences window), as well as automatically adding images found in Gmail messages. Very nice.
With all this good stuff, however, there are of course a few caveats such as being an early private beta and the fact that all your email still lives on Google's servers; i.e. - Mailplane doesn't download your email like a traditional client, it just allows you to interact with Gmail in a very powerful new way. At this early stage, however, there are a number of key elements I hope Mailplane's development focuses on. First, Mailplane implements a number of proprietary keyboard shortcuts to accomplish tasks that Gmail already has in place. For example: starring a message is cmd-*, even though pressing 's' still does the same thing. I guess this could be useful for users new to Gmail, but I wager it will be the power users after Mailplane (especially since I assume it will be a commercial app once the beta is finished), in which case they will probably be sticking to all the universal keyboard shortcuts that work no matter where or what they access Gmail from. Speaking of keyboard shortcuts, I think this is also an area where Mailplane really needs to branch out in order to capture its target audience. I use Gmail in Firefox with some Greasemonkey scripts that add serious keyboard functionality, such as navigating to labels, expanding/collapsing conversations, discarding and marking conversations as read - all from the keyboard. It's functionality like this that draws me to Gmail because these scripts make it more powerful and easier to navigate than any desktop email client I've ever used. This stuff is power user gold, and something I would be glad to pay for in a Mac OS X Cocoa application like Mailplane.
But I digress - Mailplane is a strong - and still early beta - start to an exciting application. I'm sure it has quite a ways to go yet, and plenty of us TUAW Gmail-slinging bloggers will be keeping an eye on how development evolves. For now, check out our screenshot gallery, and stay tuned here and the Mailplane blog to stay on top of this unique blend of web and desktop software.