Hi,

Find it on iTunes, it should be somewhere on there. 

Hope this helps! 

---likeabird---

You just have to connect the iPod to iTunes and then click "Check for Updates". IOS 3.1.3 should come up.

You would need to purchase the 3.1.x upgrade.

http://support.apple.com/kb/HT2052

No it isn't....

But it is slow as many other things today...

Keep trying as mine finally came up..

Here's the info from the cached page:

Purchasing iOS 3.1 Software Update for iPod touch (1st generation)

Summary

You can purchase the iOS 3.1 Software Update for iPod touch (1st generation) from the iTunes Store using the latest version of iTunes on a Mac or PC.

Purchase the iOS 3.1 Software Update directly from the iTunes Store.

Own an iPod touch (2nd generation or 3rd generation)? Get the free  iOS 4 Software Update for iPod touch.

If you are not sure which model iPod touch you have, read this article: Identifying iPod models.

Products Affected

iPod touch, iTunes Store, iTunes

After you purchase the iOS 3.1 Software Update for iPod touch, iTunes will begin downloading the software to install on your iPod touch. Note that the download make take longer on slower Internet connections (the download is approximately 250 MB). To learn more about the update process that installs the software on your iPod touch, review the following article:

• Backing Up, updating, and restoring your iPhone and iPod touch software

Additional Information

If you purchase and download the update on one computer but choose not to update your iPod touch on that computer, you can use a different computer to download the software. Simply attempt to purchase the update again as described above using the same iTunes Store account and you will be offered the option to download the update again free of charge.

Note: iPod touch (1st generation) is not compatible with iOS 4 software.

That link I gave is working right now at this minute.

I just went to it again.

Glad it worked and glad the link finally started working again.

Yesterday Apple's sites seemed to be up and down and very slow other times.

the link took me to the place in itunes to purchase and download, but every time i click purchase it says "error itunes could not purchase and unknown error occurred (5002)

I am having the same problem.  Does anyone know how to fix this?

Yeah same, i thought it was just my internet or something. all the apps i download work fine, but i can't even download many with a 2.1 ios. i bought the itunes card to get the 3.0 upgrade but i get a 5002 error every time i accept..