Have been 100% in the Permanent Portfolio since early '08 (was in Bob Clyatt's "RIP" allocation previously) and have never looked back.
What may be the longest thread ever on Bogleheads is devoted to the PP:
Bogleheads :: View topic - Updated Modification of Harry Browne Permanent Portfolio
To be clear, the Permanent Portfolio proper is 25% each Gold (preferably physical bullion - I use GTU and Bullionvault), Total Stock Market, 30 Year Treasuries and a Treasury MM fund (I use VTI, TLT and SHY). PPRFX, the mutual fund called the "Permanent Portfolio" is a decent fund but no substitute for the actual PP: it has a high expense ratio (over 1%) and is more volatile than the actual PP as it contains different assets (riskier, actively managed stocks plus Swiss francs).
It takes most people a long time to get their heads wrapped around the PP strategy - it certainly did for me coming from extensive reading of modern portfolio theory and a sophisticated slice-and-dice portfolio I'd put a lot of work into assembling. But it works, and when the market panics, as it has been lately, you'll sleep very well indeed.
Craig Rowland, seemingly the heir apparent to Harry Browne, has an excellent blog that touches on PP topics, with today's post being especially timely:
Crawling Road » A Portfolio with Firewalls