Can I edit content on an FTP server through Finder?

Is there any way around the read-only access that Finder strictly allows so I can get write access to a FTP server through Finder?

You can use MacFusion, which allows to connect to a FTP server through a filesystem device. MacFusion requires MacFUSE, or OSXFUSE with the compatibility layer for MacFUSE.

• Mount files and documents as a "Volume" in the Mac OS X Finder.
• Work with your files using your favorite Mac OS X applications directly. No manual upload or download needed!
• Support for SSH (Secure Shell) and FTP (File Transfer Protocol) servers.
• Uses your machine's native configuration for SSH, including support for private keys and custom settings.
• Quickly connect to a any server using the Quick Connect dialog, accessible from Macfusion's optional menu item.

Try Transmit.

With the new Transmit Disk feature, you can now mount any of your favorites in the Finder itself, even if Transmit's not running. These volumes are real: drag files to your SFTP server, save a small graphic to your Amazon S3 bucket directly from Photoshop, or roll your own iDisk-like backup volume. It's all possible in T4.

No you can't get around the read-only access, but here are some great FTP clients:

Cyberduck

A great free FTP client. This is my go-to application. Anytime I need FTP access, I use Cyberduck. It's not quite as lightweight as Fugu, but it adds a lot more functionality than Fugu. I like the Growl integration with Cyberduck.

Fugu

Awesome little free FTP client. As I noted above, this is a lightweight FTP client. It is great for simple FTP transfers and browsing. I do like the dual panel navigation.

Last, but not least, you can use the CLI. Just type ftp [email protected] at the prompt. If you've used the command line before, you know that ls lists directories, cd changes directories. Example: ls ~/Desktop lists the contents of your Desktop (the "~" is a shortcut for your home folder). cd ~/Desktop changes to current directory to your Desktop. To download files, you can use mget or get. Here's the Apple man page on FTP.

No, but you can use any one of many third-party FTP clients, some of which are free.

FileZilla. Open-source and cross-platform