Interesting look by 538 at the influence of cellphone polling. Not surprisingly, polls that don't factor in the 1/3 of the country without landline (i.e. people who only use cellphones, which happens to be a strongly Democratic demographic) tend to underestimate Democratic candidates.
It's also looking like the Senate is moving out of reach for the GOP, with 538 giving the GOP only about a 20% chance - or about what the same odds the Dems take the House. All that to say, it looks like we're headed toward maintaing the same alignment in the Senate and House of Reps.