Since  the User Tips aren't ready yet, I thought I would go ahead and post my  definitive guide to getting a local web server running on Lion. This is  meant to be a development platform so that you can build and test your  sites locally, then deploy to an internet server. I have instructions  for configuring the Apache, PHP, MySQL, and Perl. Now that Lion is  released, I wanted to consolidate and update all of the random bits and  pieces here on Apple Support Communities. 
Requirements:
- Basic understanding of Terminal.app and how to run command-line programs.
- Basic understanding of web servers.
- Basic usage of vi. You can substitute nano if you want.
Optional:
- Xcode is required for the MySQL driver and for adding PHP modules.
Lines in 
bold are what you will have to type in at the Terminal.
Replace 
<your local host> with the name of your machine. Ideally, it should be a one-word name with no spaces or punctuation. It just makes life easier.
Replace 
<your short user name> with your short user name.
Here goes... Enjoy!
Lion no longer creates personal web sites by default. To create one manually, enter the following:
mkdir ~/Sites
echo "<html><body><h1>My site works</h1></body></html>" > ~/Sites/index.html.en
PHP is not enabled in Lion. To enable it, do:
sudo vi /etc/apache2/httpd.conf
Uncomment line 111 that reads:
#LoadModule php5_module libexec/apache2/libphp5.so
to
LoadModule php5_module libexec/apache2/libphp5.so
Edit the launchd config file for Apache:
sudo vi /System/Library/LaunchDaemons/org.apache.httpd.plist  
Restart Apache:
sudo launchctl unload -w /System/Library/LaunchDaemons/org.apache.httpd.plist 
sudo launchctl load -w /System/Library/LaunchDaemons/org.apache.httpd.plist 
To turn on Apache, go to System Preferences > Sharing and enable Web Sharing.
NOTE: There appears to be a bug in Lion for which I haven't found a workaround. If web sharing doesn't start, just keep trying.
This might help. Might not. Remove the following from /System/Library/LaunchDaemons/org.apache.httpd.plist:
         <string>-D</string>
         <string>WEBSHARING_ON</string>
In Safari, navigate to your web site with the following address:
It should say:
It works!
Now try your user home directory:
http://<your local host>/~<your short user name> 
It should say:
My site works
Now try PHP. Create a PHP info file with:
echo "<?php echo phpinfo(); ?>" > ~/Sites/info.php
And test it by entering the following into Safari's address bar:
http://<your local host>/~<your short user name>/info.php 
You should see your PHP configuration information. This will be important for setting up MySQL later.
Download MySQL  from a local mirror. You want the Mac OS X ver. 10.6 (x86, 64-bit), DMG  Archive. Open the archive mysql-5.5.14-osx10.6-x86_64.dmg. Install only  the mysql-5.5.14-osx10.6-x86_64.pkg package. Ignore everything else.
 
Create the launchd config file for MySQL:
sudo vi /Library/LaunchDaemons/com.mysql.mysql.plist  
Use the following content:
<?xml version="1.0" encoding="UTF-8"?>
<plist version="1.0">
  <dict>
    <key>KeepAlive</key>
    <true/>
    <key>Label</key>
    <string>com.mysql.mysqld</string>
    <key>ProgramArguments</key>
    <array>
    <string>/usr/local/mysql/bin/mysqld_safe</string>
    <string>--user=mysql</string>
    </array>
  </dict>
</plist>
Create a config file for MySQL that matches the Apple PHP build:
sudo vi /etc/my.conf  
Use the following content:
[client]
socket=/var/mysql/mysql.sock
 
[mysqld]
socket=/var/mysql/mysql.sock
Start MySQL:
sudo launchctl load -w /Library/LaunchDaemons/com.mysql.mysql.plist 
 
Extract the archive with:
tar zxvf DBD-mysql-4.019.tar.gz
Move into the directory:
cd DBD-mysql-4.019
First, fix the MySQL client library. (
credit)
For Lion, type:
sudo  install_name_tool -id  /usr/local/mysql-5.5.14-osx10.6-x86_64/lib/libmysqlclient.18.dylib  /usr/local/mysql-5.5.14-osx10.6-x86_64/lib/libmysqlclient.18.dylib
Next, build DBD::mysql with:
perl Makefile.PL --mysql_config=/usr/local/mysql/bin/mysql_config --testsocket=/var/mysql/mysql.sock --testuser=root
make
make test
sudo make install
 
If you want to add modules to PHP, I suggest 
the following site.  I can't explain it any better. I had planned to update those  instructions for Lion and just give him credit, but he beat me to it.
                                             MacBook 2007 (white), Mac OS X (10.7), + iMac 27" + iPad + MacBook Pro