Quick and dirty total exonic lengths, leveraging GenomeFeatures and the Hs org package:

  hg19GeneLengths <- function(symbols)
    {
        require(TxDb.Hsapiens.UCSC.hg19.knownGene) 
        require(org.Hs.eg.db)
        exons.db = exonsBy(TxDb.Hsapiens.UCSC.hg19.knownGene, by='gene')    
        egs    = unlist(  mget(symbols[ symbols %in% keys(org.Hs.egSYMBOL2EG) ],org.Hs.egSYMBOL2EG) )
        sapply(egs,function(eg)
        {
            exons = exons.db[[eg]]
            exons = reduce(exons)
            sum( width(exons) )
        })
    }
    hg19GeneLengths( c('STAT1','CXCL10','ACTB','PDCD1') )


 STAT1 CXCL10   ACTB  PDCD1 
  4943   1216   2253   2112

John,

You could consider rentrez, which is a pretty low-level R library for the entrez API (which I wrote!).

In this case you would want to find links to other databases from your gene IDs, and then get the summary file for the refseq record:

library(rentrez)

links <- entrez_link(db = "all", ids = 353174, dbfrom = "gene")
names(links)


##  [1] "gene_bioproject"            "gene_biosystems_all"       
##  [3] "gene_cdd"                   "gene_dbvar"                
##  [5] "gene_genome"                "gene_geoprofiles"          
##  [7] "gene_gtr"                   "gene_homologene"           
##  [9] "gene_nuccore"               "gene_nuccore_mgc"          
## [11] "gene_nuccore_pos"           "gene_nuccore_refseqrna"    
## [13] "gene_nucest"                "gene_nucest_clust"         
## [15] "gene_nucleotide"            "gene_nucleotide_clust"     
## [17] "gene_nucleotide_mgc"        "gene_nucleotide_mgc_url"   
## [19] "gene_nucleotide_pos"        "gene_omim"                 
## [21] "gene_pcassay"               "gene_pcassay_proteintarget"
## [23] "gene_pccompound"            "gene_pcsubstance"          
## [25] "gene_pmc"                   "gene_probe"                
## [27] "gene_protein"               "gene_protein_refseq"       
## [29] "gene_pubmed"                "gene_pubmed_citedinomim"   
## [31] "gene_pubmed_rif"            "gene_snp"                  
## [33] "gene_snp_genegenotype"      "gene_taxonomy"             
## [35] "gene_unigene"               "gene_unists"               
## [37] "file"

Once you have ID for the refseq record, you can fetch an (unparsed) XML file with entrez_summary:

e_sum <- entrez_summary(db = "nuccore", id = links$gene_nuccore_refseqrna)
print(e_sum)

## 
## http://www.ncbi.nlm.nih.gov/entrez/query/DTD/eSummary_041029.dtd">
## <eSummaryResult>
##   <DocSum>
##     <Id>206725455</Id>
##     <Item Name="Caption" Type="String">NM_180990</Item>
##     <Item Name="Title" Type="String">Homo sapiens zinc activated ligand-gated ion channel (ZACN), mRNA</Item>
##     <Item Name="Extra" Type="String">gi|206725455|ref|NM_180990.3|[206725455]</Item>
##     <Item Name="Gi" Type="Integer">206725455</Item>
##     <Item Name="CreateDate" Type="String">2003/05/15</Item>
##     <Item Name="UpdateDate" Type="String">2012/11/11</Item>
##     <Item Name="Flags" Type="Integer">512</Item>
##     <Item Name="TaxId" Type="Integer">9606</Item>
##     <Item Name="Length" Type="Integer">1473</Item>
##     <Item Name="Status" Type="String">live</Item>
##     <Item Name="ReplacedBy" Type="String"/>
##     <Item Name="Comment" Type="String"></Item>
##   </DocSum>
## </eSummaryResult>
##

Presmusing this is the process you would go through, then wrapping it up in a function (and using Xpath to extract information from the XML) is straightforward:

get_entrez_length <- function(e_id) {
    links <- entrez_link(db = "nuccore", ids = e_id, dbfrom = "gene")
    summary_xml <- entrez_summary(db = "nuccore", id = links$gene_nuccore_refseqrna)
    len <- xpathSApply(summary_xml, "//Item[@Name='Length']", xmlValue)
    return(as.integer(len))
}

get_entrez_length(353174)

## [1] 1473

If you do use rentrez and have any questions/suggestions/bugs let me know - still developing it so happy to make it more useful.

Hey John :D

I don't have an exact solution for you, but maybe this information would help (wouldn't necessarily be quick though):

It looks like someone was coding up an R interface to eutils: http://code.google.com/p/reutils/source/browse/branches/lite/eutils.r?r=24 . I looks to me like esearch and esummary are functional enough to take queries into an XML tree. Might be more of a hassle than its worth, though.

biomaRt?