Siege: http://www.joedog.org/JoeDog/Siege

Benchmarking Laconica PHP 5.2.7-dev
 siege -H "Cookie: rememberme=13A195e06ce1b0c466b62c0d0025611fe72" \
        -c 5 "http://laconica.localhost/index.php?action=public" \
        -b -t30s
** SIEGE 2.66
** Preparing 5 concurrent users for battle.
The server is now under siege...
Lifting the server siege...      done.
Transactions:                558 hits
Availability:             100.00 %
Elapsed time:              29.83 secs
Data transferred:           5.78 MB
Response time:              0.27 secs
Transaction rate:          18.71 trans/sec
Throughput:                 0.19 MB/sec
Concurrency:                4.97
Successful transactions:     558
Failed transactions:           0
Longest transaction:        1.16
Shortest transaction:       0.05
Benchmarking Laconica - PHP 5.3.0-dev
 siege -H "Cookie: rememberme=13A195e06ce1b0c466b62c0d0025611fe72" \
        -c 5 "http://laconica.localhost/index.php?action=public" \
        -b -t30s
Transactions:                615 hits
Availability:             100.00 %
Elapsed time:              29.88 secs
Data transferred:           6.36 MB
Response time:              0.24 secs
Transaction rate:          20.58 trans/sec
Throughput:                 0.21 MB/sec
Concurrency:                4.97
Successful transactions:     615
Failed transactions:           0
Longest transaction:        7.81
Shortest transaction:       0.05

Actually not super terrible

Benchmarking Habari-0.6 - PHP 5.2.10-dev
% siege -c 5 "http://habari.localhost -b -t30s
Transactions:                345 hits
Availability:             100.00 %
Elapsed time:              30.23 secs
Data transferred:           1.74 MB
Response time:              0.43 secs
Transaction rate:          11.41 trans/sec
Throughput:                 0.06 MB/sec
Concurrency:                4.94
Successful transactions:     345
Failed transactions:           0
Longest transaction:        0.65
Shortest transaction:       0.35
Benchmarking Wordpress-2.7.1 - PHP 5.2.10-dev
% siege -c 5 "http://wordpress.localhost -b -t30s
Transactions:                219 hits
Availability:             100.00 %
Elapsed time:              30.13 secs
Data transferred:           1.07 MB
Response time:              0.68 secs
Transaction rate:           7.27 trans/sec
Throughput:                 0.04 MB/sec
Concurrency:                4.94
Successful transactions:     219
Failed transactions:           0
Longest transaction:        0.98
Shortest transaction:       0.62
Magento-1.3.0 - PHP 5.2.10-dev
% siege -c 5 "http://magento.localhost/a-widget.html -b -t30s
Transactions:                 71 hits
Availability:             100.00 %
Elapsed time:              30.42 secs
Data transferred:           1.04 MB
Response time:              2.04 secs
Transaction rate:           2.33 trans/sec
Throughput:                 0.03 MB/sec
Concurrency:                4.75
Successful transactions:      71
Failed transactions:           0
Longest transaction:        2.27
Shortest transaction:       1.85