I just checked the [urlhttp://www.dot.ca.gov/dist4/dslide/index.html]Devil's Slide project website[/url], and it looks to be open early 2012, which is a setback, of course, from the earlier projected opening of early 2011. So it looks like you'll have to battle Devil's Slide old-skool style. The information on the site seems to indicated that the existing Hwy 1 will remain open after the bypass is completed. This will then make it a nice cycling option. From what I understand, the tunnel and bridge will have excellent cycling shoulders, however.
Devil's Slide is one of the most notorious sections of the CA coast ride with often heavy, obnoxious traffic and very little to no shoulder. I've survived it three times. This time, I climbed slowly on a loaded recumbent trike, and things went pretty well. My wife did the same thing later in the season and had to deal with a particularly nasty psycho driver laying on his horn and scaring the hell out of her. One cyclist she met, a fellow who'd been riding the west coast for months, said that Devil's Slide was BY FAR the worst section he encountered. I suggest that if you have the option, do it very early on a Sunday morning. You'll bypass any commuter traffic, and heavy trucking will be at a minimum. Unfortunately, even when the new bridge and tunnel are completed, the steep, narrow, slow, shoulderless section right above Pacifica will remain unchanged. Sigh...
Scott