[BirdOPrey5]

The usergroup is not stored in $lastpostinfo...

This is all the info in $lastpostinfo on forumhome:

[forumid] => 9
    [lastpost] => 1293022161
    [lastposter] => BirdOPrey5
    [lastthread] => losers thread no bump
    [lastthreadid] => 56
    [lasticonid] => 0
    [threadcount] => 2
    [replycount] => 3
    [lastpostid] => 201
    [lastprefixid] => 
    [forumread] => 
    [styleid] => 0
    [title] => Test Forum Y
    [title_clean] => Test Forum Y
    [description] => This is a test forum with a description.
    [description_clean] => This is a test forum with a description.
    [options] => 89799
    [showprivate] => 0
    [displayorder] => 23
    [daysprune] => -1
    [icc_enable] => 0
    [icc_tags] => 
    [icc_dayrate] => 1
    [newpostemail] => 
    [newthreademail] => 
    [parentid] => 8
    [parentlist] => 9,8,1,-1
    [password] => 
    [link] => 
    [childlist] => 9,-1
    [defaultsortfield] => lastpost
    [defaultsortorder] => desc
    [imageprefix] => 
    [excludable] => 1
    [podcast] => 0
    [depth] => 2
    [permissions] => Array

To do what you'd ask you'd need to write code to fetch the usergroup based on the username, which is available... but it would mean an extra query for each forum in the list on forumhome- this would be a lot of overhead for a minor cosmetic change.