[BioC] Gene Ontology: Shortest path from root to node

[WoA [guest]]

Given some GO BP terms for a gene I wish to find out, which of the terms has more specific meaning. I wish to find out the length of the shortest path between the BP Root term(GO:0008150) and the given term. Is there any suitable way to do that using any R package? 

Like something equivalent to: 
my $length = $node->lengthOfShortestPathToRoot; 

in Perl's "GO-TermFinder" package.

Thanks in advance

 -- output of sessionInfo(): 

> sessionInfo()
R version 2.13.1 (2011-07-08)
Platform: i386-pc-mingw32/i386 (32-bit)

locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base  

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