Both chambers voted on and approved an adjournment resolution (H.Con.Res.398 - usually pass on voice vote, this one was 48-40 in the Senate), and this bit of multiple "pro forma sessions" by the Senate has been done at least 4 times (working from memory) since last year. Once in between the 1st and second sessions of the 110th Congress (Dec '07 - Jan 08), the break BEFORE that (Thanksgiving '07), and each break in 2008 (e.g., the 4th of July break).
I know that! I wish more Americans would be brought up to speed on the chicanery of the elected Dems.