The 6670 seems to be the same as the 7610, but is thicker (according to the website). The Opera browser seems to have been replaced by a Netfront browser. Is there any difference in software or functionality? Maybe the voicedialling will work this time.
Any differnce in functionality between 7610 and the 6670
Side-by-side comparison page:
http://www.nokia.com/phones/comparephones/compare_results.jsp?location=EMEA&language=EN&pageaction=COMP&phone=7610&phone=6670
In terms of software the only difference, I think, is NetFront + F-Secure Antivirus + Quickword, Quickpoint and Quicksheet.
They're both based on the same Symbian OS 7.0s and Series 60 2.1 (also known as "Series 60 Platform 2nd Edition, Feature Pack 1" in Nokia marketing terms).