Product placement done well is unnoticeable. It is when you can see it as blatant, it becomes pointless, and even contradictory.

To carry on what Edd said, how do you define product placement?
If a guy gets a coke from a vending machine, and the can is Coke Cola, is that product placement? Or every day life?
Perhaps if the people make a big deal of it or the camera lingers, then it is product placement?

Personally, I don't care, as long as it doesn't really detract from what I am watching.
I recall watching an old episode of My Family a while back where Michael wanted the new iMac (something like the G3 or the G4), could I imagine this in a real life scenario? Yes.
The last Sex in the City film, one of them has an iPhone and one of the other characters can't use it because it's new and different. If this a realistic scenario? Yes.
It does piss me off when the camera lingers. One of the new Bond films lingers far too much on the Sony equipment used in the film, you'r eyes just don't do that in real life unless it's a really cool product...

To be honest I wish there was more, discrete, product placement and less adverts as some of them are completely rubbish (especially car/razor/fragrance ads).

But... it's a Sony!

If it cut to a scene where the financial officer was saying it was in MI5's best interest to switch to Sony, fine, it's a good context (if not boring). But lingering gets on my nerves...

The recent Bond films are probably the best example of how not to do it

Think I'm pretty much agreeing with everybody else which is to say that it doesn't bother me as long as it doesn't affect the plot or the viewing.

Agreed.