I've recently upgraded one of my computers to OS X 10.7 (10.7.2).
It seems that there's no more way to show/hide the Color Panel toolbar (the one with icons at the top of the pane.
Here're some screenshots from 10.6.x then from 10.7.x (from SP 2.3.

10.6.8 with toolbar shown:

10.6.8 with toolbar hidden:

10.7.2 (no more Show/Hide button):

If you've hidden this toolbar before upgrading to Lion, there's no easy way to re-display it as there's no more Show/Hide button!
The solution I found (not necessary the only one or the easiest) is to edit the SP preferences file, setting a flag to 1 (I used Text Wrangler for this).
Here's what you need to change:
<key>NSToolbar Configuration com.apple.NSColorPanel</key>
<dict>
<key>TB Is Shown</key>
<integer>0</integer>
</dict>
setting the integer value to 1:
<key>NSToolbar Configuration com.apple.NSColorPanel</key>
<dict>
<key>TB Is Shown</key>
<integer>1</integer>
</dict>
Note that is not a specific problem of SP in Lion, I have to edit preferences files for BCC, Pixelmator and Acorn (just to name a few).
What I don't really understand is: if there's no more Show/Hide toolbar button for the Color Pane, what is the purpose of this key? Is there another way to show/hide this toolbar or is it here as a 10.6.x "relic"?