[zentiggr]

It's actually impossible for GPS to show your current position.

The signals have to be received from each satellite, then processed to yield a position valid at the time of transmission.

Every GPS fix you get is delayed by AT LEAST that processing time. Any filtering adds more lag.

Most navigation systems look at the T(fix) -> T(now) difference and project your now position from the prior fixes. Especially if you're following driving directions as opposed to free movement, then programs like Maps etc project how much further you've moved on the route, not just along your velocity vector.

After a few seconds, though, that projection will stop moving, too, when the gap between last fix and now gets too large.

[jaywalk]

The position output by a GPS receiver certainly can (will) have lag. That's probably what the poster I replied to was referring to, and I hadn't thought about it.