
Earlier today, Google pushed updates to both the Chrome beta and dev channels. The good news? Apart from other minor patches and fixes users of both testing versions on Windows 7 now see per-tab taskbar thumbnail previews.
If you haven't received the update yet, you can force a check by clicking the wrench menu and then "About Google Chrome." Downloads are also available from Google's early access channels page (
http://dev.chromium.org/getting-involved/dev-channel).
It's not without bugs, though. @keshav and I have both had a glitch which seems to occur when using win+d to show the desktop where tiny windows will appear along the top of your taskbar.

I've also experienced a problem similar to the one which plagued Firefox when support for this feature was first added: the spinning blue circle. It seems to occur mostly when (wait for it)...an uncooperative Flash embed appears on a web page.