I'm a pretty huge fan of all the new Google designs. Plus, gmail, the top bar, fonts.... They've kept things minimalistic while making things just feel cleaner and crisper. Whoever is leading this redesign is doing a fantastic job.
[1] Who wrote In the Plex.
[2] http://www.wired.com/epicenter/2011/06/inside-google-plus-so...
That said, the left pane of the new gmail interface looks a little too spartan at first blush. Maybe I'll get used to it but it looks a little unfinished to me now.
I jumped into an email thread and it feels like I'm reading the soot filled footprints of ancient Siberians crossing the glacial land bridge: everything's surrounded by so much white!
In this new design it's hard for my eyes to stay focused on the actual content.
If you're trying to move away from the "40 shades of blue" while keeping a fun and playful feel, why not use green?
Green button: https://img.skitch.com/20110701-pff56qthuqr89t77d2x3u2smhj.p...
Grey button: https://img.skitch.com/20110701-wwxrad2urrj1xjmanusme8w9w.pn...
I now think the red works best too (but felt the same way as you about it at first). Other colours stand out against the red "Mail" and "Inbox" links, which gives a somewhat technicoloured dreamcoat feel to the UI. They could change the red links to green, but then they lose the connection with the red 'M' envelope character, as you rightly point out. A light grey might work, but probably wouldn't stand out enough for new users.
*that, and because Sprint isn't getting the Pre 3.
Ref: http://googleblog.blogspot.com/2011/06/evolving-google-desig...
"Hertzfeld, who has been working at Google since 2005, is indeed the one we can thank for the better-looking interface on Google+, as he’s the design lead on the project."
He was the lead for the design, not just the circles features.