I prefer the apostrophe-free version myself, but for what it's worth, apostrophes for plural acronyms seem to be fairly accepted. Here's an example from an nyti

I prefer the apostrophe-free version myself, but for what it's worth, apostrophes for plural acronyms seem to be fairly accepted. Here's an example from an nytimes blog: http://www.nytimes.com/adx/bin/adx_click.html?type=goto&opzn&page=blog.nytimes.com/freakonomics&pos=Bar1&sn2=4c064693/12cbd2ee&sn1=830c3a64/99f17898&camp=nyt2010-circ-tr-bar1_international_366RU&ad=093009-TR_bar1_366RU&goto=http%3A%2F%2Ftimesreader%2Enytimes%2Ecom%2Ftimesreader%2Findex%2Ehtml%3FcampaignId%3D366RU http://www.nytimes.com/adx/bin/adx_click.html?type=goto&... Grammar public defense attorney out :-)