Robert Plant to join Buddy Miller onstage in San Francisco tonight; John Paul Jones and Jason Bonham also gigging in U.S. this evening

Boz Scaggs is hosting the second of two charity gigs in San Francisco tonight, and word was released only hours in advance that Robert Plant would be making an appearance.

Plant will be sitting in on a song with Buddy Miller, a Nashville native and recent recipient of multiple Americana awards. Miller was part of the touring band that accompanied Plant and Alison Krauss worldwide last year.

Plant really seems to have caught the Buddy Miller bug. Last July, they recorded a track together backstage at one of their gigs. It appeared this March on Buddy's latest album with his wife, Julie Miller. But before that, on Sept. 18, 2008, Plant and Buddy Miller played their song together in front of an audience during their first onstage appearance without Krauss.

The only other times Plant has graced a stage this year were on April 25 at a Womad concert in Abu Dhabi and on Sept. 11 at a charity concert in London, both times with Justin Adams, formerly Plant's guitarist in the Strange Sensation, and Adams's latest touring companion, Gambian musician Juldeh Camara.

Buddy Miller has been doing a lot of things too. The poor guy, who had a heart attack last year, is said to be pulling long hours working every week and suffering from the affliction of not knowing how to say no to people.

But judging from the vacant touring schedule currently shown at www.buddyandjulie.com, he hasn't had anything scheduled since July. This may mean Miller's date book is wide open if Plant suggests they do something a little more permanent together than just tonight's one song at the charity gig.

The other possibility is that Miller simply hasn't gotten his scheduled gigs up on that site and he really is booked. For instance, in addition to assisting Boz Scaggs this week, he's booked to appear at the Hardly Strictly Bluegrass Festival tomorrow. There, just as tonight and last night, Miller's part of Boz Scaggs & the Blue Velvet Band, which also features blues harmonica player James Cotton among others. They play at the Rooster Stage at 2:30 p.m. tomorrow, and the festival is a free three-day concert at Speedway Meadow in Golden Gate Park. Who knows if Plant may show up there too!

Plant's impromptu appearance in San Francisco tonight could not have come on a more interesting night, which is also seeing Jason Bonham at the Mirage in Las Vegas with Slash and Friends, plus John Paul Jones playing twice in one day at the Austin City Limits Festival in Texas: first with Sara Watkins (as confirmed by LedZeppelinNews.com in advance of the set) and second with Them Crooked Vultures. I have been following all three of these events on Twitter tonight.