Yosemite Valley 

Effective July 31st access twice daily east/west bound with pilot car. See link for details and times.

www.inciweb.org/incident/news/article/236/820/

getting there without a car:
from San Francisco airport:
bart (local train, www.bart.gov) to Richmond Station
change there to amtrak
amtrak (www.amtrak.com) train to Merced
yarts bus (www.yarts.com) from Merced to the valley

Not many bouldering problems posted on MP. Looking to boulder check out an excellent guide my Matt Wilder. Yosemite Valley Bouldering by SuperTopo. www.supertopo.com/packs/yosemiteboulder.html

A good link to Valley Bouldering - betabase.blogspot.com/

Yosemite Valley Guidebooks that are currently available:

Supertopo Bigwalls - $30
54 of the finest Bigwalls in the Valley. Highly accurate and detailed route information. If you want to climb walls, this is the book to buy. Now in it's 3rd edition, with an emphasis on bigwall free climbing. 208 Pages. Full color.

Supertopo Road to the Nose - $15
More of an training/instructional guide than an area guidebook. It does include topos for the Nose and a handful of other wall routes in the Valley, in addition to some cragging. 60 Pages. Full color.

Supertopo Free Climbs - $30
Accurate route information and interesting history. With only 230 routes, this is more of a "select" guide. Folks visiting for the first time will likely want to pick this one up. 209 pages. B&W.

Supertopo Sport Climbs and Topropes - $20
The Valley is not the best place to go sport climbing or toproping, but if that's what you intend on doing, then I guess this is the book for you. If you are looking to sport climb in the 5.11+ to 5.13 range, you'd probably be better off picking up the Reid guide which has more of the stuff at Public Sanitation Wall and other hard sport areas. 120 Pages. Full color.

Supertopo Bouldering - $28
Many people overlook the bouldering in the Valley, but it's truly world-class. This is the best (and really only) guidebook for the Valley's bouldering. 160 pages. Full color.

Falcon Guide Free Climbs - $25
aka the "Reid guide". The most comprehensive guidebook to the Valley, and what Valley regulars will want to buy. Route information is often vague and somewhat suspect (beware the "pro to 3"), but with more than 10 times as many routes as Supertopo's, this guidebook is what you need to escape the crowds. 432 Pages. B&W.

Falcon Guide Free Climbs Select - $15
At only a marginally reduced price from the regular guidebook, this gutted version isn't really worth it. If you want a select guide, get the Supertopo. This is, however, the only book to feature "the blowhole" sport crag at Wawona tunnel. 144 Pages. B&W.

A literal mecca? Thousands of climbing days a year?

That's thousands of "climber-days," not climbing days. Which is different. If that clarification is necessary!