Intel has posted an upgrade service page on their website which indicates that Intel will again be offering upgradeable CPUs. This is not totally unheard of since Intel offered a similar service for Pentium G6951 a year ago. Back then, $50 bought you Hyper-Threading and 1MB more L3 cache, and the SKU of the CPU changed to G6952. This time Intel has expanded the lineup and the upgrade service is available for three CPUs: i3-2312M, i3-2102 and Pentium G622. Unfortunately we don't know the price yet but we do know that the upgrade offers higher frequency and possibly increased amount of cache. Here are the CPU before and after the upgrade:
CPU Before Upgrade CPU After Upgrade Performance increase i3-2312M (2.1GHz, 3MB) i3-2393M (2.5GHz, 4MB) 10-19% i3-2102 (3.1GHz, 3MB) i3-2153 (3.6GHz, 3MB) 12-15% Pentium G622 (2.6GHz, 3MB) Pentium G693 (3.2GHz, 3MB) 15-23%
The after CPUs have not been released so the specs are just calculations based on the performance gains Intel reported.
Upgrading the CPU is very simple. All you need is the upgrade card. Then download the installer from Intel's site and run it. At some point, you will be asked to insert the code from the upgrade card (no, you can't get this for free).
The need for such upgrade is fairly small though. We don't know the price so it's hard to say can the upgrade be worth it or not, but if the price will end up being $50 like before, it's pretty expensive for 10-23% gains. Pentium G622 costs only ~$65, meaning that you get 23% performance increase for 77% more money. Not exactly a bargain. i3s cost a bit more but even then, you aren't getting a good performance/price ratio.
The only useful scenario could be with OEM PCs when you may not be able to select a specific CPU and upgrading the CPU can be harder (or even impossible) and may void the warranty. Intel has blocked overclocking in non-K CPUs, so you are stuck with the stock frequency. In some rare occasions where the extra CPU speed is really needed, paying the upgrade price can be worth it. However, what we are looking at are low-end CPUs, so anyone who needs a powerful CPU should look at Intel's i5 and i7 lineups in the first place.