The 106th Senate consisted of 46 Democrats and 54 Republicans and 0 Independents. The 107th Congress, just elected, has 50 Democratic and 50 Republican Senators.
This claim will be judged TRUE if a Senator not affiliated with either the parties currently named "Republican" or "Democratic" is sworn in by the end of 2011. If no such Senator is sworn in, the claim will be judged FALSE.
It is not necessary for the Senator in question to be from one of the fifty states that exist at the claim creation date, nor for them to be elected in an even-year election. (Example: if a Republican Senator dies and a replacement election is held in 2005, at which a Green Party candidate wins and is sworn in, the claim will be judged TRUE.) The Senator in question also need not be from a party at all.
I will judge this claim based on the intent of the claim.
Note that a switch of parties while in office is not sufficient to make this claim true. An election of a Senator with a non-Republican non-Democratic party affiliation must occur and that Senator must be sworn into office without switching to either of those parties prior to being sworn in, OR a Senator must be elected from any party and officially/publically switch to a non-Rep/Dem affiliation prior to being sworn into the Senate.