What we have here is yet another tantalizing screen grab of Ice Cream Sandwich, the fourth iteration of the Android smartphone operating system from Google. ICS will make its official debut in North America this week onboard the Galaxy Nexus, which is already on sale in the UK. But thanks to CyanogenMod I’m running it on my Nexus S right now.

Google should obviously get due credit for releasing the Android 4.0 source code a few weeks back, but it’s this alpha version of CM 9 that makes running it possible on last year’s Android flagship.

And for alpha software it’s incredibly polished — I haven’t tried making a voice call yet (do people still do that?) but everything else seems to work. I do get one recurring error message, something like: “Exchange services have stopped working”, but my email and calendar apps don’t seem to be affected by it.

Verizon users take note: The forthcoming version of CyanogenMod comes bundled with Google Wallet. Though it’s only supposed to be available for use in the USA with a Citibank MasterCard I was able to activate a $10 welcome gift and (ahem) make the first-ever NFC purchase from a mobile phone in Canada. Someone wanna get that on Wikipedia for me?

Back to the title of the post… You’d think this delicious taste of ICS would have me chomping at the bit for a Galaxy Nexus to call my own. Well as it turns out, not so much. And all because of three simple letters: MTP, or Media Transfer Protocol.

This won’t be an issue for Windows or even Mac users, but this user of desktop Linux was dismayed to find that he couldn’t mount his Nexus as a filesystem while it was running CM 9. Google has decided that only ICS devices with actual removable memory will have USB Mass Storage Mode (UMS). You can read the summary points of an informal Q&A with a Google dev on reddit here.

Long story short, Ice Cream Sandwich supports UMS, but the Galaxy Nexus will not. Ditto for my Nexus S.

In addition to the existing MTP library (libmtp) on my Linux Mint 11 box I added mtp-tools, mtpfs, gmtp… but it made no difference. As I dug deeper into mount points and such I started to wonder if the problem wasn’t my computer but the storage on my phone, or physical lack thereof.

There are certainly workarounds — AirDroid, Dropbox, etc. — someone on Twitter even suggested that I try accessing my Nexus through a music player, which I’ve always thought was kind of a stupid idea.

Given the brilliance they’ve demonstrated thus far it’s not inconceivable that the Cyanogen team could somehow bring UMS support to handsets without physical storage, but this might be too much to ask, even of them. Until it happens (if ever) I’m going to give the Google’s late 2011 flagship a pass, and thank Steve Kondik and co. for providing me with the opportunity to find this out now, rather than when I find myself six hundred and fifty dollars out of pocket.

I’m not bashing the Galaxy Nexus, it’s just not for me. So what other ICS-compatible handset could possibly take its place? Come back next Wednesday and find out if you like…