I use Google Apps like no one’s business and it’s the only system that I’ll use to power my personal and professional emailing services. It really is king.
But, there isn’t a picture-perfect desktop application for it (yet) and I am hoping that MailPlane for the Mac might be it. Take a look at this overview video:
Essentially the goal of this application is to take your Gmail to the next level, optimizing attachments, allowing greater and more-easy switching between accounts (I have more than a few), notifications, and more.
It’s not free after the first 30 days so if you like it make the purchase. If not, continue to hope that a better one comes out!