You're trying to figure out what a hiring manager will value... and that can be tricky. My experience is mostly with companies doing systems programming, compilers, and embedded software.
I've worked at two companies who had a minimum GPA to be considered, but it wasn't too onerous. (3.0 out of 4) Some hiring managers view overall GPA as a half decent "performance evaluation" of the candidate over a long term period, and a decent measure of self-motivation. This is not entirely inaccurate.
When I'm hiring, I will look at GPA as something of a base requirement. Do I really want to hire someone who managed to spend four years of his life and how-many thousands of dollars, and couldn't put forth enough effort to beat a 2.5? Frankly, in order to even look at a below-B-average student, they need to have absolutely stellar projects on the side that they've been working on. (core components of a large open source project would be acceptable, for example... senior thesis would not be)
On the other side of the coin, the difference between a 3.3 GPA and a 3.9 GPA is negligible from an employers standpoint. A 4.0 is notable, but a bit of a bias exists that the "4.0 student" is really aiming for academia, and may leave soon to pursue that goal. Others in this thread mention that some employers insist on a 3.5, but I haven't personally come across them.
In summary, I would work hard to keep your grades above a 3.5. At least at my school, it was several orders of magnitude more difficult to maintain a 4.0 (or just short of it) from a 3.6-3.7 range. While that first job you want might not require it, you won't be shut out of interesting opportunities with a "high A-B student" grade, and you very well may get more out of your classes anyway.
"First Job only": Some have mentioned that the employers after the first don't really care about grades. While this is true to a great extent, it's also true that there are "job development paths", and it's much easier to move to higher paying positions if you start out at a higher-paying/more-technically-challenging first job, which will often have more strict requirements.