One poll shows a convention "bounce" for Romney, while Michigan is close, or not really. Here's our guide to today's polls and why they matter. 

Findings: In a national rolling poll Romney now leads Obama 44 to 42 percent. 
Pollster: Reuters/Ipsos 
Methodology: Online interviews with 1,481 registered voters in a four-day rolling poll taken August 26 through 30 with a "credibility interval" of +/-2.9 percentage points. 
Why it matters: According to Reuters' Steve Holland, the numbers out today suggest that Romney got a "small bounce" from the convention. At the beginning of the week, in the first installment of the rolling poll, Obama led 46 to 42 percent.
Caveat: Obama might get a "bounce" next week from his convention. Also, these numbers were released before Romney's speech last night.  

Findings: Obama leads 49 percent to 46 percent in Michigan.
Pollster: EPIC-MRA 
Methodology: Automated poll of 1,200 likely voters August 28 with a margin of error of +/-2.6 percentage points.
Why it matters: Recent polls out of Michigan have indicated that the state might have a tight race on its hands. In a July EPIC-MRA poll Obama led by a comfier six points, according to the Detroit Free Press' Todd Spangler. The Mitchell poll has also indicated a similar shift: Obama's lead dropped to a tie from a five-point lead.
Caveat: All that said, Five Thirty Eight's Nate Silver cautioned earlier this week that Michigan isn't a "tossup." Silver points out that national polls working in the state show Obama with a bigger lead while in-state polls, such as this one, make the race seem much closer. Also, as Spangler notes, the poll was taken before some key speeches at the convention occurred.