Compact Flourescent Brightness

I recently purchased a couple GE CFL bulbs, and noticed an interesting
phenomenon.  When I first turn these bulbs on, they are much dimmer than
expected, but over the course of 30 to 60 seconds they become noticeably
brighter.  Is it normal for flourescents to get brighter as they warm up?
I've never noticed this before with other flourescent lighting.

Also, does anyone make a CFL bulb which is the equivalent of a 75W
incandescent?  The ones I've seen have all been 60W and 100W equivalents.

M.