Browsing pubmed to put off going to work, I came across this abstract:
"On the 1st hour after ethanol administration, the ethanol concentrations in blood of the theanine combined groups decreased compared with the ethanol-alone group. The alcohol dehydrogenase and aldehyde dehydrogenase activities in the liver increased by combined theanine."
Those two enzymes turn alcohol into (more toxic) acetaldehyde, and acetaldehyde into (non-toxic) acetic acid. So if this is true, its seems to corroborate the anecdotes posted here about tea after drinking helping folks sober up.
Enjoy, N.