It normally is installed by adding a bookmark on your Mac/PC and syncing your iPhone with that.

This post will show you how to install it on Linux without using iTunes.

Download the Safary Bookmark file from your iphone.
For firmware 1.1.3 this is in /private/var/mobile/Library/Safari/Bookmarks.plist

Use plutil to convert the binary playlist file to text
so you can modify it:

perl plutil.pl Bookmarks.plist

You’ll find a file named Bookmarks.text.plist

in which you can a new entry for Tabulate:

<dict>
    <key>URIDictionary</key>
    <dict>
        <key>title</key>

        <string>Tabulate - bring open in new tab to iphone</string>
    </dict>
    <key>URLString</key>
    <string>javascript:(function(){head=document.getElementsByTagName('head')[0];if(head){s=document.createElement('script');s.setAttribute('src','http://gadgets.inventivelabs.com.au/tabulate/script');head.appendChild(s);}else{alert('Tabulate-error:document-invalid');}})()</string>

    <key>WebBookmarkType</key>
    <string>WebBookmarkTypeLeaf</string>
    <key>WebBookmarkUUID</key>
    <string>78B2DD0B-3978-4773-8ED0-419027E79BD6</string>

</dict>

All you need to do is to convert your text file to binary, rename it and copy
it back to your iPhone again:

perl plutil.pl Bookmarks.text.plist
mv Bookmarks.binary.plist Bookmarks.plist
scp Bookmarks.plist root@iphone/private/var/mobile/Library/Safari/

To make Safari use the new Bookmarks reboot it by pressing the home button for about 5 seconds.

I’ve been searching for a way to use my SIP account on my iPhone for ages and now and
finally found a solution.

SIP-VoIP by Touchmods is meant for the iTouch. When using it on the iPhone you can call and hear people, but they won’t hear you.

Siphon currently only support SIP accounts at freephonie.net.
I tried to make it use another server by editing /Applications/Siphon.app/accounts.xml but this did not help out.
Somebody had a great idea to change /etc/hosts to make freephonie.net resolve to your server. This might work for your account on an asterisk box, but did not work for my UTA SIP account.

However, Siphon looks promising: You can also select the contacts of your iPhone’s addressbook.
According to the homepage, Siphon will be extended to work for other operators too:

The service will be extended to all iPhone and iPod Touch (with the Touchmods microphone) users,
independently of their operator, subject to availability of the SIP service

Today, Zauchi showed me fring. fring allows you to use services like skype, icq, and many more.
You can even make phone calls using you sip account, and update your Twitter profile.

I tried out icq, skype (only chatting), sip phone calls and twitter – all worked like a charm.
What I can tell by now is that the notification beep is getting on your nerves soon. You can only get rid of it by muting your iPhone completely.
fring will need a lot of time to start up, if you’ve got mutliple communities activated (about 1 minute for skype, icq, sip and twitter) and you can’t choose you iPhone’s contacts for VoIP calls.

It also looks like there is no way to only activate certain accounts as you can do in Apollo IM. This could speed up the application launch and also allow users to make a skype call without going online in iqc.

fring is still beta, so i’m sure some of the downsides mentioned above will be fixed in the next releases.

As far as I can tell yet, fring definitely is on the way of getting a real iPhone killer app!