my @logentries = ();
my $toss = 1;
my $monthRegex = join("|",qw/Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec/);
while (<LOGDATA>) {
   if(/^($monthRegex)\s+d{1,2}\s+(\d{2}:){3}/) {
      push(@logentries,$_); $toss = 0;
      # unless you want to ignore some of'em
      # in which case: $toss++;
   } else {
      $logentries[$#logentries] .= $_ unless $toss;
   }
}
foreach (@logentries) {
# decide what to do with each entry,
# handling XML content with a suitable module when necessary
}