Yeah, the real package name is Intellinav (iGuidance, PrymeNav, Routis) v2. Here's a review:
http://www.gpspassion.com/fr/articles.asp?id=100
I'll definitely be buying v2... I love v1, but unless I'm missing something, it doesn't have the ability to mark roads as 'avoid' due to closure, construction, etc. That was a MAJOR pain for me last weekend, let me tell you! But v2 has it. Yay.
v2 of iGuidance started shipping June 25:
http://www.inavcorp.com/products/iguidance2.html
And regarding the GPS accuracy, it's more likely that your GPS receiver has: A) an obstructed view of the sky B) A view of the sky above at a time when most satellites are at lower positions in the sky C) Difficulty reading signals with multipath interference as generated by buildings close to the receiving antenna.
The localized interference as I understand it is more like jamming: ie no signal lock, rather than intentional misrepresentation of location... Probably more to do with your receiver... I'm sure different receivers have different tolerances before they decide their lock is lost.