Solid enough thriller fare, it's all fairly standard in execution (excuse the pun), except this flick takes a look online instead of the typical serial killer/nutjob/whatever wacko that you might usually see stalking around such a film.
I've always maintained that this avenue of plot remains to be mined, heck it's taken 24 till its seventh season to get around to cyber terrorism (a shame then that we'll have to wait until 2009 to see that awesomeness unfold).
Anyway, think somewhere along the lines of SAW ... then tame it back a fair bit ... then wrap it in the facade of a more mainstream thriller complete with swooping crane shots and almost constantly calm cinematography, and you've got Untraceable.
Watchable, occasionally rather grim, but generally formulaic and predictable. Diane Lane is enjoyable to watch, but limited by the by-the-numbers script, and Colin Hanks is both entertaining and love-able, it's just a shame he hasn't had much meat to chew thus far into his career - but then again it is early days for him.