$ { echo some text; echo; tail -n1 /var/log/apache2/error.log; } >> /path/to/file
June 22, 2012, 5:29 p.m. — Janos
All the standard output from all the commands between the braces will be redirected.
$ echo -e "From: me\n\n$(tail -n1 /var/log/apache2/error.log)" >> file
June 21, 2012, 8:18 p.m. — kevin
-e
$(command)
The -e flag of echo doesn't work on all systems. In that case you can use printf instead.
echo
printf