This thread on R-devel led me to write these functions to search into R mailing list archives through gmane. 
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#' search on gmane.org mailing list archives
#'
#' @param string query
#' @param group search on which gmane group
#' @param author author of the email
#' @param sort sort order criteria
#' @param op how to combine words
#' @param r.group R related group to use, the default "*" means all r related groups
gmaneSearch <- function( string, 
    group = paste( "gmane.comp.lang.r.", r.group, sep = ""), 
    author = "", sort = c("relevance", "date", "revdate"), 
    op = c("and", "or"), 
    r.group = "*" ){
    
    sort <- match.arg(sort)
    op <- match.arg( op )
    
    url <- sprintf( 
        'http://search.gmane.org/?query=%s&author=%s&group=%s&sort=%s&DEFAULTOP=%s', 
            gsub( ' +', '+', string),  author,  group,  sort, op )
    url <- URLencode( url )
    browseURL( url )
}

#' retrieves the list of gmane groups associated with a prefix
#' 
#' @param prefix group prefix
gmaneGroups <- function( prefix = "gmane.comp.lang.r." ){
    url <- URLencode( sprintf( "http://dir.gmane.org/index.php?prefix=%s", prefix) )
    txt <- grep( '^<tr.*<td align=right.*<a', readLines( url ), value = TRUE )
    
    rx <- '^.*?<a href="(.*?)">(.*?)</a>.*<td>(.*?)</td>.*$'
    out <- data.frame( 
        url = gsub( rx, "\\1", txt ), 
        group = gsub( rx, "\\2", txt ),
        description = gsub( rx, "\\3", txt ), 
        stringsAsFactors = FALSE
        )
    out$group <- sub( "...", ".*", out$group, fixed = TRUE )
    out
}

So for example: 

R> gmaneSearch ("browser prompt", author="romain" )
pops up this page