It is just a copy and paste kind of hack to get it advertised in each forum. The bottom line is that RSS feeds are picked up by search engines. The more traffic to Avast is a good thing, isn't it?
http://www.simplemachines.org/community/index.php?topic=20339.0SMF Features
Feature list of SMF 1.0
General
Uses PHP and MySQL.
Comprehensive template system.
Advanced permission and user management.
Supports multiple languages at once.
Open and well-documented source code.
Tracking of new and old unread topics, not just from your last visit.
Designed for optimal performance and scalability.
Multi-media output. (XHTML, XML, RSS, WAP)
Multi-language support from a large community.
Package manager that automatically installs or uninstalls mods (also known as hacks.)