In a word... no. I doubt any sane fan expects them to maintain a 1.00 ERA for 162 games, but does this early stretch mean pre-season projections need to be adjusted? Well, not really. The O's starters have certainly pitched well, but their strike-out to walk ratio is a solid but unspectacular 2.2 - which would have ranked right between Derek Lowe and Rick Porcello last year. The pitchers have benefited from (1) the defense turning over 80% of balls in play into outs (which is just not going to continue), and (2) flyballs staying in the park (they've given up just one home run despite being one of the least groundball inducing staffs in the majors so far). That explains why their ERA is so far out of line with their FIP (2.79) and xFIP (4.23). Now, if the O's posted a 4.23 ERA for the season that would still be a pretty substantial improvement over 2010 (when they had a 4.59 ERA), but that level of run prevention would not result in a ton of wins with the offensive production they've been getting.
For a (somewhat simplified) look at what the team's record would be based on their underlying stats (xFIP, wRC, UZR, etc.), check out Orioles Beyond W & L at the top of the site (or here). The sample size is obviously very small, so take it with a grain of salt for a little while yet.
Stats: ERA, FIP, xFIP, BABIP, HR/FB%